Here we have another page of addition which looks at adding three numbers. Each number is a multiple of 5, but there is an extra twist in that children need to work out how many different additions can be made from the numbers available.
A systematic approach is needed, perhaps starting with the largest three numbers;
i.e. 75 + 65 + 55
then moving on to the next largest;
i.e. 75 + 65 + 45
and so on.
An important part of this is to understand that addition can be done in any order so 75 + 65 + 55 is the same as 55 + 65 + 75.