By the supplementary angles theorem, we know that both of the angles add up to equal 180°, so:
(4x + 22) + (8x - 10) = 180
12x + 12 = 180
12x = 168
x = 14
Now you just have to plug in x into the value for ∠ABC:
∠ABC = 4x + 22
∠ABC = 4(14) + 22
∠ABC = 46 + 22
∠ABC = 68°
