SOLUTION: Sandy's mother's age is now four times Sandy's age. Five years from now, Sandy's age will be one third of his mother's age. How old is Sandy now?
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Question 1141880: Sandy's mother's age is now four times Sandy's age. Five years from now, Sandy's age will be one third of his mother's age. How old is Sandy now?
since m = 4 * s in the first equation, replace m with 4 * s in the second equation to get:
s + 5 = 1/3 * (4 * s + 5)
multiply both sides of this equation by 3 to get:
3 * (s + 5) = 4 * s + 5
simplify to get:
3 * s + 15 = 4 * s + 5
subtract 3 * s from both sides of this equation and subtract 5 from both sides of this equation to get:
10 = s
that's sandra's age now.
her mother's age now is 4 * 10 = 40
5 years from now, sandra will be 15 and her mother will be 45.
her mother is 4 times sandra's age now (40 / 10 = 4)
her mother will be 3 times sandra'a age in 5 years (45 / 15 = 3)
when her mother's age is 3 times sandra's age, sandra's age will be 1/3 * her mother's age.
that's because m = 3 * s in 5 years.
divide both sides of that equation by 3 to get m/3 = s
if her mother's age is 3 times sandra's age, than sandra's age is 1/3 time her mother's age.
your solution is that sandra's age now is 10 years old.
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