SOLUTION: Peter is 12 years older than his brother David. If
four times Peter’s age plus two times David’s age
is 66, how old are Peter and David?
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-> SOLUTION: Peter is 12 years older than his brother David. If
four times Peter’s age plus two times David’s age
is 66, how old are Peter and David?
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Question 392388: Peter is 12 years older than his brother David. If
four times Peter’s age plus two times David’s age
is 66, how old are Peter and David? Answer by fafa(13) (Show Source):
You can put this solution on YOUR website! peter=P
david=D
first formula is P=12+D (because peter is 12 years older thn David)
the second formula is 4P+2D=66 (because four times Peter’s age plus two times David’s age is 66)
and then we substitute the first formula to the second formula
4P + 2D = 66
4(12+D) + 2D = 66
48 + 4D + 2D = 66
48 + 6D = 66
48 - 48 + 6D = 66 - 48
6D=18
6D : 6 = 18:6
D= 3
so David is 3 years old
P = 12 + D
P = 12 + 3
P = 15
so peter is 15 years old
