1) (x + 3) * 5 = 725
x + 3 = 725/5
x + 3 = 145
x = 145 - 3 = 142
2) 4949 ÷ 7 + x = 20678
707 + x = 20678
x = 20678 - 707
x = 19971
3) 2 * x + 908 = 4052
2 * x = 4052 - 908
2 * x = 3144
x = 3144/2 = 1572
4) 5 * b - 1209 = 1256
5 * b = 1256 + 1209
5 * b = 2465
b = 493