Chris C.

asked • 11/30/16

Word Problems

Maggie’s brother is three years younger the twice her age. The sum of their ages is 24. How old is Maggie?

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Gj C. answered • 11/30/16

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Brother = 2 x Maggie - 3
Brother + Maggie = 24
Brother = x, Maggie = Y
x = 2y - 3
x + Y =24
 
substitute
 
2y - 3 + y = 24
3y = 27
y = 9
 
x + 9 = 24
x = 15
 
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Chris C.

i dont understand. 
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11/30/16

Gj C.

Since you have 2 unknowns, Maggie and her brother you need to put the information given into 2 equations. 
Brother = 2 x Maggie - 3
Brother + Maggie = 24
Then let the Brother = x and  Maggie = Y
x = 2y - 3
x + Y =24
 
The first equation already has the variable, x alone on one side of the equation. 
So since x = 2y -3
you can substitute 2y -3 in for x in the 2nd equation
x + y = 24 becomes (2y - 3) + y = 24 Now there is only 1 variable so you can solve it.
combine the y terms 2y + y -3 = 24 becomes 3y - 3 = 24
now move the 3 to the other side of the equation 3y -3 +3 = 24 + 3 which become3y = 27
then move the 3 to the other side by doing the inverse operation 3y /3 = 27/3 so y = 9
 
That this value for y and put it into the x + y = 24 equation, which gives you x + 9 =24
do the inverse operation to move the 9 to the other side so x + 9 - 9 = 24 - 9 and x =15
good luck!
 
 
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11/30/16

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