Question 997523: Mr. Santos is twice as old as his son. In six years, he will be three times what his son’s age was, six years ago. How old is Mr.Santos now?
Answer by addingup(3677)   (Show Source):
You can put this solution on YOUR website! S= 2s <--Mr. Santos is twice his son's age
S+6= 3(s-6) Watch the parenthesis. It's 3 times (current age-6) and not 3 times current age and the result minus 6. First you subtract 6 from current age, then you multiply times 3
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We said above that S= 2s, so let's use this value for S in the next formula:
S+6= 3(s-6) Substitute:
= 2s+6= 3(s-6) Multiply on right to get rid of parenthesis:
2s+6= 3s-18 Add 18 to both sides and subtract 2s from both sides:
24= 1s or 24= s. More elegantly:
s= 24 The son is 24 years old. And the father, the problem says:
2*24= 48 And in 6 years he will be his son's age less 6 times 3:
Father in 6 years: 48+6= 54 And the problem says:
(24-6)*3= 18*3= 54 We have the correct answer.
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