AC = 46
AB + BC = AC
(4x + 7) + (3x + 4) = 46
4x + 7 + 3x + 4 = 46
(4x + 3x) + (7 + 4) = 46
7x + 11 = 46
7x = 46 - 11
7x = 35
x = 35/7
x = 5
AB = 4x + 7
AB = 4(5) + 7
AB = 20 + 7
AB = 27
BC = 3x + 4
BC = 3(5) + 4
BC = 15 + 4
BC = 19
