Question

the cost of a carpet 7 m long is rs. 1400. if the breadth were 1m less , the cost would have been rs1200 . find the cost per msquare of the carpet

Answer 1

Let the breadth of carpet = x m
length = 7m
Area = 7x m²
cost = Rs. 1400 
cost per square meter = 1400/ 7x = Rs. 200/x

if the breadth were 1m less breadth = (x-1) m 
area = 7(x-1) m²
cost = Rs. 1200
cost per meter square = Rs. 1200/ 7(x-1)

$\frac{200}{x}= \frac{1200}{7(x-1)} \\ \\ \Rightarrow 200 \times 7 \times (x-1) = 1200 x\\ \\ \Rightarrow 1400x -1400 = 1200 x\\ \\ \Rightarrow 200x =1400\\ \\ \Rightarrow x = 1400/200= 7 m$

Cost per square meter = 200/x = Rs. 200/7