а) 1,5(1 + x) = 4,5
1,5 + 1,5x = 4,5
1,5x = 4,5 - 1,5
1,5x = 3
x = 3 / 1,5
x = 2

б) 2(x - 7) = 1
2x - 14 = 1
2x = 1 + 14
2x = 15
x = 15 / 2
x = 7,5