(a) Tom says that 1/5 + 7/20 = 8/25

Explain why he is wrong and show how to work out the correct answer.

(b) Show that 3/4 divided by 1 7/8 = 2/5

9. (a) Jadar is buying fencing to fence one side of his garden. He measures the length as 23cm to the nearest metre.

What is the largest possible true length of the garden?

(b) One post measures 180 cm truncated to 2 significant figures (Truncated means that rather than rounding, any digits after 2 significant figures are simply ignored