Solve the proportion for u.

(u-2):(u+3) = 4:3

(u-2):(u+3) = 4:3

(u - 2)/(u + 3) = 4/3
3(u - 2) = 4(u + 3)
3u - 6 = 4u + 12
u = - 18

-18 - 2 = - 20
-18 + 3 = - 15

-20:-15 = 4:3