First __work out how many balloons he will need to buy__. In order __for each bag to have two balloons__, he will need 70 balloons. __Since he can buy 20 balloons at a time__, this implies the minimum number he would need is 80 balloons (as it is the __smallest multiple of 20 which is bigger than 70__ – use number line to help visualise), or __four bags of balloons__. Therefore __he needs to spend 4 times £1.33 on balloons__, i.e. he needs to spend £5.32 on balloons.Now let’s work out the same thing but for sweets. __Since only one of the balloons will have a sweet inside it, each bag only needs one sweet__ meaning he only needs to get 35 sweets. Since he can only buy 15 sweets at a time, this implies the minimum number he would need is 45 sweets (as it is the smallest multiple of 15 which is bigger than 35), or three bags of sweets. Therefore __he needs to spend 3 times £2.05 on sweets__, i.e. he needs to spend £6.15 on sweets.Finally, we need to __add these two numbers together to get the total cost__ of the gift bags, meaning they will cost a total of £5.32+£6.15=£11.47