Constructing Equations Example A table top measures x cm by y cm. Write down an expression for its area, A.

Example The sides of a rectangle are A cm and B cm. Write down an expression for the perimeter of the rectangle.

Example A packet of chewing gum holds 8 sticks of gum. How many sticks are there in 3 packets 8 packets x packets?

Example A classroom in the new building is designed to hold 35 pupils. How many pupils can be seated in 2 rooms 5 rooms R rooms?

Example The number B is the sum of two numbers x and y. write down an expression for B.

Example The cost of a pen is 9 pence. What is the cost of 3 pens 12 pens n pens?

Example Alan is three years younger than his sister Fiona. If Fiona is y years old write down an expression for Alan’s Age. If Fiona’s mum is three times her age. Write down an expression for her age.

Example The sum of three numbers is S and two of the numbers are a and b. What is the third number ?

Example A pen and pencil together costs x pence, and a pen alone costs y pence. Find the cost of three pencils.

Example The cost of a school outing to the theatre is £ C for the hire of the coach plus £5 per child for tickets Write down an expression for the cost of 20 children When n children attend the theatre the total cost is £ T Write a formula for T in terms of C and n.

Example A bag of sweets is handed around the class and each student takes 4 sweets from the bag. If there are C people in the class, how many sweets are taken from the bag? If there are 5 sweets left in the bag, and there were S sweets in the bag at the start, write down a formula connecting S and C.