Mother and daughter

The mother is four times older than her daughter. Five years ago, her daughter was seven times younger than her mother. How many years do they have now?

Correct answer:

d =  10
m =  40

Step-by-step explanation:


m=4d
m-5 = 7·(d-5)

m=4·d
m-5 = 7·(d-5)

4d-m = 0
7d-m = 30

Pivot: Row 1 ↔ Row 2
7d-m = 30
4d-m = 0

Row 2 - 4/7 · Row 1 → Row 2
7d-m = 30
-0.43m = -17.14


m = -17.14285714/-0.42857143 = 40
d = 30+m/7 = 30+40/7 = 10

d = 10
m = 40

Our linear equations calculator calculates it.



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