SOLUTION: Michelle is 3 years older than her sister. In 10 year's time the sum of there ages will be 77 years. How old is each of them now.

Question 957436: Michelle is 3 years older than her sister. In 10 year's time the sum of there ages will be 77 years. How old is each of them now.
Answer by macston(5194) (Show Source): You can put this solution on YOUR website!
M=Michelle's age; S=sister's age=M-3yrs
(M+10yrs)+(S+10yrs)=77yrs Subtract 20yrs from each side.
M+S=57yrs Substitute for S.
M+(M-3yrs)=57yrs Add 3yrs to each side.
2M=60yrs Divide each side by 2.
M=30 yrs ANSWER 1: Michelle is 30 years old.
S=M-3yrs=30yrs-3yrs=27 yrs ANSWER 2: Sister is 27 years old.
CHECK:
(M+10yrs)+(S+10yrs)=77yrs
(30+10yrs)+(27+10yrs)=77yrs
40yrs+37yrs=77yrs
77yrs=77yrs

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