SOLUTION: Dad is seven times as old as his son. 10 years later, he will be three times as old as his son. Find their ages.

Question 834119: Dad is seven times as old as his son. 10 years later, he will be three times as old as his son. Find their ages.
Answer by jim_thompson5910(35256) (Show Source): You can put this solution on YOUR website!
"Dad is seven times as old as his son" ---> D = 7S

"10 years later, he will be three times as old as his son" ---> D+10 = 3(S+10)

D+10 = 3(S+10)

7S+10 = 3(S+10)

7S+10 = 3S+30

7S = 3S+30-10

7S-3S = 30-10

4S = 20

S = 20/4

S = 5 <--- The son is 5 years old

D = 7S

D = 7*5

D = 35 <---- The dad is 35 years old.
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