Wall area = rectangular area+triangular area =4×5+5× 1.2÷2=23 square meters.

* * * Brick: 23× 185=4255.

The fourth question:

( 1):

2×6+(8+4.6)×3/2+(6.6+2)×3/2+3.2×3/2

= 12+24.4×3/2

= 12+36.6

=48.6(cm？ )

(2):

2×6+(8+4.6)×3/2+(6.6+2)×3/2+3.2×3/2

= 12+24.4×3/2

= 12+36.6

=48.6(cm？ )

45×2 1÷48.6

=945÷48.6

≈ 19