The sides of a rectangle are in the ratio 5: 4. If its perimeter is 72 cm then what will be the length therectangle?

The problem involves finding the length of a rectangle given the ratio of its sides and its perimeter. Here are the steps to solve it:

Step 1: Understand the problem The ratio of the sides of the rectangle is 5:4. This means that for every 5 units of length, there are 4 units of width. The perimeter of the rectangle is given as 72 cm.

Step 2: Set up the equation The formula for the perimeter of a rectangle is 2*(length + width). Since we know the ratio of the sides, we can express the length as 5x and the width as 4x. Substituting these into the formula gives us 2*(5x + 4x) = 72.

Step 3: Solve the equation Solving the equation 2*(5x + 4x) = 72, we get 18x = 72. Dividing both sides by 18, we get x = 4.

Step 4: Find the length Substitute x = 4 into the expression for the length, we get length = 5x = 5*4 = 20 cm.

So, the length of the rectangle is 20 cm.