a) 5x/6 = 70 => 5x = 420 => x = 420/5 => x = 84
b) 2x/3 = 3 • 240/4 => 2x/3 = 720/4 => 2x/3 = 180 => 2x = 180 • 3 => 2x = 540 => x = 540/2 => x = 270
c) 4x/5 = 3 • 56/4 => 4x/5 = 42 => 4x = 210 => x = 210/4 => x = 105/2 => x = 52,5
d) (1/4 + 1/3)x = 34(3/10) => (3+4)x/7 = (340+3)/10 => 7x/7 = 343/10 => x = 34,3