Odpowiedź:
a) 40%x = 12
0,4x = 12
x = 30
b) 40%x = 20
0,4x = 20
x = 50
c) 30%x = 24
0,3x = 24
x = 80
d) 20%x = 3
0,2x = 3
x = 15
e) 80%x = 32
0,8x = 32
x = 40
f) 70%x = 140
0,7x = 140
x = 200
g) 90% x = 27
0,9x = 27
h) 15%x = 24
0,15x = 24
x = 160
