SOLUTION: Mary is 12 years old. Robin her mother is 35. a. Write an expression for the person’s age y years from now. b. Write an equation stating that Robin is twice as old as Mary. How

Algebra ->  Customizable Word Problem Solvers  -> Age -> SOLUTION: Mary is 12 years old. Robin her mother is 35. a. Write an expression for the person’s age y years from now. b. Write an equation stating that Robin is twice as old as Mary. How      Log On

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Question 170510: Mary is 12 years old. Robin her mother is 35.
a. Write an expression for the person’s age y years from now.
b. Write an equation stating that Robin is twice as old as Mary. How old will they both be at this time?
c. What will their ages be when Robin is 3 times as old as Mary
I know that expression for the person's age y years from now is:
Mary: 12 + y
Robin: 35 + y

Answer by Mathtut(3670) About Me  (Show Source):
You can put this solution on YOUR website!
b. so when is robin twice as old as mary. Take you expressions
:
robin (35+y)=2 mary's 2(12+y)
:
35+y=24+2y--->combine like terms
:
y=11------->so robin will be 35%2B11=46and Mary will be12%2B11=23
:
c. this time we have robin(35+y)=3 mary's(12+y)
:
35+y=3(12+y)
:
35+y=36+3y-->combine like terms
:
y=-1/2 so Robin was 35-1%2F2=34.5 and Mary was 12-1%2F2=11.5