C ONSTRUCTING E QUATIONS  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 (i) 3 packets (ii) 8 packets (iii) x packets?

 Example A classroom in the new building is designed to hold 35 pupils. How many pupils can be seated in (i) 2 rooms (ii) 5 rooms (iii) 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 (i) 3 pens (ii) 12 pens (iii) 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 a) Write down an expression for the cost of 20 children b) 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. a) If there are C people in the class, how many sweets are taken from the bag? b) 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.