The width of a rectangle is X cm.
 The length is 1·5 cm more than the width.
 The perimeter of the rectangle is 17 cm. Write down an equation satisfied by X
 and solve it to find X.

Let's call the length 'L', and the width 'X'. Since the length is 1.5cm more than width, we can form the equation: L = X + 1.5 (Equation 1)Let's call the perimeter 'P'. Therefore, we know that P = 17cm. For now, we shall ignore the units (cm), so P = 17.Since a rectangle has 2 'widths' and 2 'lengths', we know that the total perimeter (P) is equal to 2X + 2L. This means that we can also form the equation: P = 2X + 2L = 17 (Equation 2)We now want to form an equation solely in terms of 'X' or 'L'. This will make it easier to solve the question.We can do this by subbing Equation 1 into Equation 2: 2(X+1.5) + 2X = 17 (Equation 3)By multiplying out the bracket, we now know that 4X = 14. This means that X = 14/4 => X = 3.5cm.Using Equation 1, L = X + 1.5 = 3.5 + 1.5 => L = 5cmCHECK: We can check our solution by making sure that our answers add up to equal the original perimeter (P).From Equation 2:2L + 2X = 2 x 5 + 2 x 3.5 = 17cm. Therefore, we have calculated the correct answer.