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3 years ago

Jack is 4 times as old as Lacy. 3 years from now the sum of their ages will be 71 . How old are they now?

Mathematics

1 answer:

Marizza181 [45]3 years ago

3 0

Answer:

Lacy is 13 and Jack is 52

Step-by-step explanation:

In 3 years their ages will add up to 71 so you have to subtract 6 as there are two of them to get 65. Lacy's age is represented by x and since Jack is 4 times older his age is represented by 4x. So added together their age is 5x. So 5x=65. Then 65/5=13. So 13=x. So Lacy is 13 and Jack is 52 as 13x4 is 52.

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Solve the following using Substitution method 2x – 5y = -13 3x + 4y = 15

Digiron [165]

$\huge \boxed{\mathfrak{Question} \downarrow}$

Solve the following using Substitution method

2x – 5y = -13

3x + 4y = 15

$\large \boxed{\mathfrak{Answer \: with \: Explanation} \downarrow}$

$\left. \begin{array} { l } { 2 x - 5 y = - 13 } \\ { 3 x + 4 y = 15 } \end{array} \right.$

To solve a pair of equations using substitution, first solve one of the equations for one of the variables. Then substitute the result for that variable in the other equation.

$2x-5y=-13, \: 3x+4y=15$

Choose one of the equations and solve it for x by isolating x on the left-hand side of the equal sign. I'm choosing the 1st equation for now.

$2x-5y=-13$

Add 5y to both sides of the equation.

$2x=5y-13$

Divide both sides by 2.

$x=\frac{1}{2}\left(5y-13\right) \\$

Multiply $\frac{1}{2}\\$ times 5y - 13.

$x=\frac{5}{2}y-\frac{13}{2} \\$

Substitute $\frac{5y-13}{2}\\$ for x in the other equation, 3x + 4y = 15.

$3\left(\frac{5}{2}y-\frac{13}{2}\right)+4y=15 \\$

Multiply 3 times $\frac{5y-13}{2}\\$ .

$\frac{15}{2}y-\frac{39}{2}+4y=15 \\$

Add $\frac{15y}{2} \\$ to 4y.

$\frac{23}{2}y-\frac{39}{2}=15 \\$

Add $\frac{39}{2}\\$ to both sides of the equation.

$\frac{23}{2}y=\frac{69}{2} \\$

Divide both sides of the equation by 23/2, which is the same as multiplying both sides by the reciprocal of the fraction.

$\large \underline{ \underline{ \sf \: y=3 }}$

Substitute 3 for y in $x=\frac{5}{2}y-\frac{13}{2}\\$ . Because the resulting equation contains only one variable, you can solve for x directly.

$x=\frac{5}{2}\times 3-\frac{13}{2} \\$

Multiply 5/2 times 3.

$x=\frac{15-13}{2} \\$

Add $-\frac{13}{2}\\$ to $\frac{15}{2}\\$ by finding a common denominator and adding the numerators. Then reduce the fraction to its lowest terms if possible.

$\large\underline{ \underline{ \sf \: x=1 }}$

The system is now solved. The value of x & y will be 1 & 3 respectively.

$\huge\boxed{ \boxed{\bf \: x=1, \: y=3 }}$

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Lerok [7]

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Andre45 [30]

Answer:

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Step-by-step explanation:

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3 years ago

What is the ratio of red sections to total sections, in lowest terms?

Tanzania [10]

Hello there! Your answer would be 1/4.

So to start, count up the total number of sections, and the number of red sections. There are 16 sections total, and 4 of them are red.

This can give us the ratio 4/16.

But next we need to simplify. What is the biggest number that can be divided by both 4 and 16? 4. So, divide both 4 and 16 by 4 to get your simplified answer.

4÷4/16÷4

1/4

So, the ratio of red sections to total sections, in lowest terms is 1/4.

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4 years ago

Read 2 more answers

Solve. -4 is greater than -4/3s −4 > − 4/3 s

alekssr [168]

Answer:

s>3

Step-by-step explanation:

Step 1: Flip the equation.

-4/3s <-4

Step 2: Multiply both sides by 3/(-4).

(3/-4) x (-4/3s) < (3/-4) x (-4)

s > 3

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3 years ago