From 2nd to 3rd level the height increase = 35 - 26 = 9vsk wrote:Please help to solve this. Thanks.

The height of 1st level = 26 - 9 =17

To reach height of 89 cm the levels needed = (89 - 17 )/9 + 1

(since each height increase by 9 cm)

= 8 + 1 = 9

(a) He need 9 levels to reach 89 cm

(b) Observing the base, for 2 level he has 2 solid as base, for 3 levels he has 3 solid, so for 9 levels, he need = 9+8+7+6+5+4+3+2+1

= 45 solids