SOLUTION: 4. Marilyn is 3 years younger than her friend Rosie. In 7 years, the product of their ages will be thrice the product of their ages 5 years ago. How old are they at present?

Algebra ->  Customizable Word Problem Solvers  -> Age -> SOLUTION: 4. Marilyn is 3 years younger than her friend Rosie. In 7 years, the product of their ages will be thrice the product of their ages 5 years ago. How old are they at present?       Log On

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Question 1164690: 4. Marilyn is 3 years younger than her friend Rosie. In 7 years, the product of their ages will be thrice the product of their ages 5 years ago. How old are they at present?
Answer by josgarithmetic(39617) About Me  (Show Source):
You can put this solution on YOUR website!
system%28m=r-3%2C%28m%2B7%29%28r%2B7%29=3%28m-5%29%28r-5%29%29

Substitute for m, first.
%28r-3%2B7%29%28r%2B7%29=3%28r-3-5%29%28r-5%29
%28r%2B4%29%28r%2B7%29=3%28r-8%29%28r-5%29
r%5E2%2B11r%2B28=3%28r%5E2-13r%2B40%29
r%5E2%2B11r%2B28=3r%5E2-39r%2B120
3r%5E2-r%5E2-39r-11r%2B120-28=0
2r%5E2-50r%2B92=0
r%5E2-25r%2B46=0
Factorable.
%28r-23%29%28r-2%29=0

Most likely highlight%28r=23%29 and highlight%28m=20%29.