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3 years ago

Abigail is 8 years older than Cynthia. Twenty years ago Abigail was three times as old as Cynthia. How old is each now?

Mathematics

2 answers:

koban [17]3 years ago

7 0

Hey!

A=32 years C=24 years

irina [24]3 years ago

5 0

A - age of Abigail
C - age of Cynthia

A = C + 8

A - 20 = 3 (C - 20)

A - 20 = 3C - 60

C + 8 - 20 = 3C - 60

C - 12 = 3C - 60 A = C + 8

2C = 48 A = 24 + 8

C = 24 years A = 32 years

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The correct answer is C !

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Please could you explain this step by step I’m really stuck.

allochka39001 [22]

Answer:

x = -2.5
x = 2

Step-by-step explanation:

Hello!

We can remove the denominators by multiplying everything by it.

Solve:

$\frac{5}{x + 3} + \frac4{x + 2} = 2$
$5 + \frac{4(x + 3)}{x + 2} = 2(x + 3)$
$5 + \frac{4x + 12}{x + 2} = 2x + 6$
$5(x + 2) +4x + 12 = (2x + 6)(x + 2)$
$5x + 10 + 4x + 12 = 2x^2 + 6x + 4x + 12$
$9x + 22 = 2x^2 + 10x + 12$

Let's make one side equal to 0.

$0 = 2x^2 + x - 10$

Solve by factoring, and then the zero product property.

$0 = 2x^2 + x - 10\\$

Multiply 2 and -10. You get -20. Think of two number that multiply to -20, and add to 1. If we think about the standard form of a quadratic, $ax^2 + bx + c$ , think two numbers that equal "ac" and add up to "b".

$0 = 2x^2 - 4x + 5x - 10$
$0 = 2x(x - 2) + 5(x - 2)$
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Using the zero product property, set each factor to 0 and solve for x.

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The two answers are x = -2.5, and x = 2.

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1 year ago

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Wittaler [7]

Answer:

Step-by-step explanation:

−

n+\frac{5}{16}=-1

n+165=−1

Solve

Subtract

\frac{5}{16}

165

from both sides of the equation

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n+\frac{5}{16}=-1

n+165=−1

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n+\frac{5}{16}{\color{#c92786}{-\frac{5}{16}}}=-1{\color{#c92786}{-\frac{5}{16}}}

n+165−165=−1−165

Simplify

Solution

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2 years ago

natima [27]

Answer:

See explanation

Step-by-step explanation:

Let x be the number of spade shovels, y -the number of flat shovels and z - the number of square showels sold that day.

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x+y+z=80

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x=2z

The total cost of all shovels is

16x+9.60y+12.80z=1,072

a) The system of three equations is

$\left\{\begin{array}{l}x+y+z=80\\ \\x=2z\\ \\16x+9.60y+12.80z=1,072\end{array}\right.$

b) In matrix form this is

$\left(\begin{array}{ccc}1&1&1\\ 1&0&-2\\ 16&9.60&12.80\end{array}\right)\cdot \left(\begin{array}{c}x\\y\\z\end{array}\right)=\left(\begin{array}{c}80\\0\\1,072\end{array}\right)$

c) The determinant is

$\left\|\begin{array}{ccc}1&1&1\\ 1&0&-2\\ 16&9.60&12.80\end{array}\right\|=0-32+9.60-0+19.20-12.80=-16$

d) Find three determinants:

$\left\|\begin{array}{ccc}80&1&1\\ 0&0&-2\\ 1,072&9.60&12.80\end{array}\right\|=0-2,144+0-0+1,536-0=-608$

$\left\|\begin{array}{ccc}1&80&1\\ 1&0&-2\\ 16&1,072&12.80\end{array}\right\|=0-2,560+1,072-0+2,144-1,024=-368$

$\left\|\begin{array}{ccc}1&1&80\\ 1&0&0\\ 16&9.60&1,072\end{array}\right\|=0+0+768-0-0-1,072=-304$

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$x=\dfrac{-608}{-16}=38\\ \\y=\dfrac{-368}{-16}=23\\ \\z=\dfrac{-304}{-16}=19$

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