Mother and daughter

Three years ago, the mother was three times older than the daughter. After nine years, she will be only twice old.

How old is the mother (and daughter)?

Correct answer:

m =  39
d =  15

Step-by-step explanation:


m-3=3(d-3)
m+9=2(d+9)

m-3=3·(d-3)
m+9=2·(d+9)

3d-m = 6
2d-m = -9

Row 2 - 2/3 · Row 1 → Row 2
3d-m = 6
-0.33m = -13


m = -13/-0.33333333 = 39
d = 6+m/3 = 6+39/3 = 15

d = 15
m = 39

Our linear equations calculator calculates it.



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