Question

if 20 metre of cloth cost rupees 180 how much would 75 metre cost

Answer 1

cost of 75 metre cloth will be = 75*180/20
= Rs 675

Answer 2

Cost of 20m cloth = ₹180
Cost of 1m cloth = 180/20 = ₹9
Cost of 75m cloth = 75 * 9 = ₹675

Using Simple unitary method...