SOLUTION: Your client needs a total of five mirrors in his house. If the width of the mirror is 120 cm and the length is 360 cm, find the cost of framing it at the rate of Rs.10 for 20 cms.
According to the problem's context, you need to determine the perimeter of one mirror;
then multiply it by 5 to get the total perimeter of 5 mirrors;
then multiply the total perimeter of 5 mirrors by the rate.
Having these instructions, you should be able to do the rest on your own.