Question 931668
x sister's age.  Manual (x+8)
.......
3 years ago..
(x+8) - 3 = 3(x-3)
x + 5 = 3x - 9
14 = 2x
7 = x, sister's age .  Manual is 15 {{{7+8}}}
And checking...3 years ago
12 = 3(4)