SOLUTION: I really can't figure out how to solve age word problems and I'm stuck on this one. If David's brother is 3 years older than him, and the sum of their ages is 17, how old is David?

Question 955929: I really can't figure out how to solve age word problems and I'm stuck on this one. If David's brother is 3 years older than him, and the sum of their ages is 17, how old is David? So if you wouldn't mind helping me, I would be so thankful.
Answer by macston(5194) (Show Source): You can put this solution on YOUR website!
D=David's age; B=brother's age=D+3
D+B=17 Since B=D+3, it follows:
D+(D+3)=17 Subtract 3 from each side.
2D=14 Divide each side by 2
D=7 ANSWER 1: David is 7 years old.
B=D+3=7+3=10 ANSWER 2:David's brother is 10 years old.
CHECK:
D+B=17
7+10=17
17=17
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