Răspuns:
1.
15%×280=
=15/100 × 280
=15/10 × 28
=3/2 × 28
=3 × 14
=42 lei reducere
preț nou 280-42=238 lei
2.
320 elevi
cl.a V-a: 3/8 × 320 =3×40=120
rest: 320-120=200
cl.a VI-a: 11/25 × 200 =11×8=88
rest: 200-88=112
cl.a VII-a: 3/4 × 112 =3×28=74
cl.a VIII-a: 112-74=38