Question 128414
The sum of ages of 4 family members is 68. Four years ago the sum was 53. How old is the youngest family member? Please EXPLAIN!
:
let their ages (going from the youngest) = a, b, c ,d
:
a + b + c + d = 68
:
the 4 year ago equation
(a-4) + (b-4) + (c-4) + (d - 4) = 53
a + b + c + d - 16 = 53
then
a + b + c + d = 53 + 16
a + b + c + d = 69; which is not possible,
:
We can assume that "a" was not born 4 years ago
Then 4 yrs ago:
(b-4) + (c-4) + (d-4) = 53
b + c + d - 12 = 53
b + c + d = 53 + 12
b + c + d = 65
:
Therefore:
a = 68 - 65
a = 3 yrs old