va rog eu foarte rapid 4,5, 6, 7

4x/x4 = 7/4
(40 + x)/(10x + 4) = 7/4
160 + 4x = 70x + 28
160 - 28 = 70x - 4x
66x = 132
x = 132 : 66
x = 2
3a = 4b => a = 4b/3
inlocuim
6a = xb
6×4b/3 = xb
24b = 3xb | : b
3x = 24
x = 8
a/3 = 4/b => a = 12/b
a/b = (12/b)/b = 12/b : b/1 = 12/b x 1/b = 12/b²