Răspuns:
a) 9r +28=2755
9r=2755-28
9r = 2727
r =2727:9
r = 303
c) 3(x +7) = 75
3x + 21 = 75
3x = 75 - 21
3x = 54
x = 54 : 3
x = 18
510 + 14 x = 762
14x = 762 -510
14x = 252
x = 252 :14
x = 18
14(12- x) = 70
168 -14x = 70
168 -70 = 14x
98 = 14x
x= 98 : 14
x= 7
(82+y):6=17
82+y=17×6
82+y=102
y=102 - 82
y = 20
410 - 7y = 151
410 - 151 = 7y
259 = 7y
y = 259 : 7
y = 37
5x + 52 -31=302-19
5x+21= 290
5x = 290 - 21
5x=269
x=269:5
x= 53,8