Mensuration
b) the dimensions of a wall is 30 m x 5m x 20 cm. it contains three windows each
of 3m x 1.5 m. how many bricks of size 20 cm x 10 cm x 5 cm are required to
build the wall leaving 10% of the space for the cement work? also find the cost of
bricks at the rate of rs 9000 per 1000 bricks,

Step-by-step explanation:

1. Number of bricks

(a) Volume of wall without windows

V = lwh = 30 m × 0.20 m × 5 m = 30 m³

(b) Volume of windows

   One window: V = 1.5 m × 0.20 m × 3 m = 0.9 m³

Three window : V = 3 × 0.90 m³ = 2.7 m³

(c) Volume of wall with window openings

V = 30 m³ - 2.7 m³ =27.3 m³

(d) Volume of cement work

V = 0.10 × 27.3 m³ = 2.73 m³

(e) Volume of bricks

V = 27.3 m³ - 2.73 m³ =24.57 m³

(f) Volume of one brick

V = 0.20 m × 0.10 m × 0.05 m = 0.001 m³

(g) Number of bricks

2. Cost of bricks

i believe that the answer is

b. y-1=-2(x-4)

hope this !