Answer:
Melissa =13 years
Becky = 12 years
Daniel =10 years
All share $28 in the ratio of their ages.
Becky gives a third of her share to her mother.
B : D : M : : 12 : 10 : 13
Becky's $28 = $9.60
Becky has left with =$6.40.
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Step-by-step explanation:
30/150 = 80/x
Reduce the fraction:
1/5 = 80/x
Cross multiply:
x = 5 x 80
x= 400
Answer: 400 zebras.
Answer: OPTION B.
Step-by-step explanation:
Given the following System of equations:
You can use the Elimination Method to solve it. The steps are:
1. You can mutliply the second equation by -3.
2. Then you must add the equations.
3. Solve for the variable "y".
Then:
4. Now that you know the value of the variable "y", you must substitute it into any original equation.
5. The final step is to solve for "x" in order to find its value.
Then:
Therefore, the solution is:
Let x be the cost of 1 pen
then cost of 1 notebook = x + 8.20
Let y be the number of pens Tan buys
then number of notebooks Tan buys = y/4
She spent $26 more on books than on pens which means
Cost of notebooks - Cost of pens = 26
(x + 8.20) * y/4 - xy = 26
Sinplifying it
(xy + 8.20y)/4 - xy = 26
(xy + 8.20y - 4xy)/4 = 26
8.20y - 3xy = 104
She spent $394 which means
Cost of notebooks + Cost of pens = 394
(x + 8.20) * y/4 + xy = 394
Simplifying it
(xy + 8.20y)/4 + xy = 394
(xy + 8.20y + 4xy)/4 = 394
8.20y + 5xy = 1576
Now, we have two equations,
(1) 8.20y - 3xy = 104
(2) 8.20y + 5xy = 1576
Now we need to find a third equation with either x or y as the subject of any of both the previous equations.
Let's make y the subject of (2) equation
8.20y + 5xy = 1576
y(8.20 + 5X) = 1576
(3) y = 1576/(8.20 + 5x)
Let's substitute the new value of y from (3) into (1) because we rearranged (2) to from (3)
8.20y - 3xy = 104
y(8.20 - 3x) = 104
y = 104/(8.20 - 3x)
1576/(8.20 + 5x) = 104/(8.20 - 3x)
1576 * (8.20 - 3x) = 104 * (8.20 + 5x)
12923.2 - 4728x = 852.8 + 520x
12923.2 - 852.8 = 4728x + 520x
12070.4 = 5248x
12070.4/5248 = x
x = 2.3
Now find the value of y by substituting the value of x in either equation, preferably (3)
y = 1576/(8.20 + 5x)
y = 1576/(8.20 + 5 * (2.3))
y = 80
Therefore cost of 1 notebook = x + 8.20 = 2.3 + 8.20 = $10.50
Essentially when people ask you find the solution to system of equation, there asking at what x value do these to graphs intersect. The easiest way to do this is to get a graphing calculator, or desmos and type in the equation and find where they intersect. Heck, even the question says to solve it with a graph, but I'll demonstrate it algebraically.
One way you can do this is set the equation equal to each other. This is because you want to know at what x-value has the same y-value. So we get:
x^2 + 6x + 8 = x + 4
We can then combine like terms, or move everything to one side. So we get:
x^2 + 5x + 4 = 0.
Then we can use the quadratic formula to solve for x.
x=(-5 +/- sqrt(5^2 - 4(1)(4)))/(2(1)
This simplifies into:
(-5 +/- 3)/2
Finally we add and subtract:
(-5 + 3)/2 = x = -1
(-5 - 3)/2 = x = -4
And our solution is x = -1, x = -4
