Years 7729

Five years ago, Adam was seven times more than Peter and ten years more than Peter. How old is Adam older than Peter?

Correct answer:

x =  18

Step-by-step explanation:


a-5 = 7(p-5)
a+10 = 2(p+10)
x = a-p


a-5 = 7·(p-5)
a+10 = 2·(p+10)
x = a-p

a-7p = -30
a-2p = 10
a-p-x = 0

Row 2 - Row 1 → Row 2
a-7p = -30
5p = 40
a-p-x = 0

Row 3 - Row 1 → Row 3
a-7p = -30
5p = 40
6p-x = 30

Pivot: Row 2 ↔ Row 3
a-7p = -30
6p-x = 30
5p = 40

Row 3 - 5/6 · Row 2 → Row 3
a-7p = -30
6p-x = 30
0.833x = 15


x = 15/0.83333333 = 18
p = 30+x/6 = 30+18/6 = 8
a = -30+7p = -30+7 · 8 = 26

a = 26
p = 8
x = 18

Our linear equations calculator calculates it.



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