7 * a - 15 : 3 + 9 = 60
7 * a - 5 + 9 = 60
7*a + 4 = 60
7 * a = 60 - 4
7 * a = 56
a = 56 : 7
a = 8
17 + 72 : b * 10 - 32 = 74
17 + 72 : 10 * b - 32 = 74
72 : 10* b = 74 + 32 - 17
72 : 10 * b = 89
72 = 89 * 10 * b
72 = 890 b
b = 72 : 890
b = 0 , 08
(Nu cred ca al doilea e bine... )
