Taking LCM of 5 and 2 = 10 on LHS and LCM of 3 and 1 = 3 on RHS

By cross multiplication

⇒ 3(4x + 14 - 15x - 55) = 10(2x - 7)

⇒ 3( - 11x - 41) = 20x - 70

⇒ - 33x - 20x = 123 - 70