Răspuns:
a) x=12
b) x=16
c) x=20
d) x=28
Explicație pas cu pas:
a) 3/100=x/400
x=3×400/100
x=3×4
x=12
b) 4/100=x/400
x=4×400/100
x=4×4
x=16
c) 5/100=x/400
x=5×400/100
x=5×4
x=20
d) 7/100=x/400
x=7×400/100
x=7×4
x=28
