a) ( a+18) x 3 : 6 + 70 = 130
( a+ 18) x 3 : 6 = 130 - 70 = 60
( a+18) x 3 = 60 x 6 =360
a + 18 = 360 : 3 = 120
a = 120 - 18 =102
b) ( a + 18 x 3) : 6 + 70 = 130
( a+ 18 x 3) : 6 = 130 - 70 =60
a + 18 x 3 = 60 x 6 = 360
a + 18 = 360 : 3 = 120
a = 120 - 18 = 102