A = -3b/4
(4a + 3 b - a + 2b) / (4 a + 3 b + a + 4b) = (2b - a) / (a + 4b) = (2b-(-3b/4)) / (-3b/4 + 4b)=
= (11b/4) / (13b/4)= (11b * 4) / (13b * 4) = 11/13
5дм-17 см+4 дм8см= 50 см -17 см + 48 см=33+48=81 см
6м3дм+ 42дм-3м6дм=63дм+42дм-36дм=105-36=69дм