SOLUTION: A grandmother is taking her granddaughter to the movies. The grandmother is 9 years less than 7 times the age of the granddaughter. The sum of their ages is 71. Let (x) stand for t

Question 521054: A grandmother is taking her granddaughter to the movies. The grandmother is 9 years less than 7 times the age of the granddaughter. The sum of their ages is 71. Let (x) stand for the granddaughter's age and (y) stand for the grandmother's age.
Answer by mamiya(56) (Show Source): You can put this solution on YOUR website!
A grandmother is taking her granddaughter to the movies. The grandmother is 9 years less than 7 times the age of the granddaughter. The sum of their ages is 71. Let (x) stand for the granddaughter's age and (y) stand for the grandmother's age.
the grandmother is 9 years less than 7 times the age of the granddaughter, means
y= 7x - 9
the sum of their ages is 71, means y + x=71
so we have, y - 7x = -9
y + x=71
we subtract the second equation from the first one,
(y-7x)-(y+x)= -9-71
y-7x-y-x= -80
-8x= -80
x= (-80)/(-8)
x = 10
and y=7*10 -9=61
so the grandmother is 61 and the granddaughter is 10.
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