Adriel is x years old and her younger sister is y years old. the sum of thei ages is 7. the difference of 3 times adriels age and her sisters age is 9. the related sum of the linear equation is x+y=7 3x-y=9. solve the linear equations. then find adriels age and her sisters age

set one of the equations to equal x or y

(substitution method)

x=7-y plug this into the other equation

3(7-y)-y=9 distribute

21-3y-y=9 --> 21-4y=9

get y alone

-4y=9-21--> -4y=-12 divide by -4 to solve

y=3 sisters age

plug this in to one of the equations to get Adriel's age

x+3=7

x=7-3

x=4 Adriel's age

why can't you?

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146%

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