Triangle WHA and WCT are similar, so corresponding parts are similar to one another. In particular,
WH / WC = WA / WT = HA / CT
which means
WH / WC = WA / WT
2 / (2 + (x - 1)) = 3 / (3 + (x + 1))
Solve for x :
2 / (1 + x) = 3 / (4 + x)
2 (4 + x) = 3 (1 + x)
8 + 2x = 3 + 3x
5 = x
and also
WH / WC = HA / CT
2 / (1 + x) = y / 12
2 / (1 + 5) = y / 12
2 / 6 = y / 12
y = 4
