Question 1119161: a woman is older dan her daughter by 15 yrs, 10 yrs ago the ratio of their age was 4,1 find thier present age Found 3 solutions by josgarithmetic, ikleyn, greenestamps:Answer by josgarithmetic(39618) (Show Source):
W = D + 15, (1)
= 4. (2)
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W - 10 = 4*D - 40
(D + 15) - 10 = 4*D - 40
D + 5 = 4*D - 40
5 + 40 = 4*D - D
45 = 3*D ====> D = = 15.
Answer. The daughter is 15 years old. The women is (15+15) = 30 years old.
If the woman is 15 years older than her daughter, then when the ratio of their ages was 4:1 their ages had to be 20 and 5. That was 10 years ago; so now the mother is 30 and the daughter is 15.
There was a bit of mental arithmetic there....
If the ratio of two numbers is 4:1, then the two numbers can be represented by 4x and x; the difference between the two numbers is then 4x-x = 3x. Since the difference in ages is 15, 3x=15 so x=5. Then the ages (10 years ago) were x=5 and 4x=20; the current ages are 5+10=15 and 20+10=30.