Resposta :
a) x +9 = 13
x = 13 - 9
x = 4
b)x-7= 10
x = 10+7
x = 17
c) 5x – 1=9
5x = 9+1
5x = 10
x = 10/5
x = 2
d) x - 3=8
x = 8+3
x = 11
a) x +9 = 13
x = 13 - 9
x = 4
b)x-7= 10
x = 10+7
x = 17
c) 5x – 1=9
5x = 9+1
5x = 10
x = 10/5
x = 2
d) x - 3=8
x = 8+3
x = 11