You should ask your teacher if you don't get this bit.
The question doesn't ask how many bananas are bought so you needn't work it out. You are given quantities and the price per quantity - it's addition.A person buys some stuff add the total.
Apples cost £2 per KG
Oranges £0.34 each
Bananas £2.40 per KG
A person buys
1 KG of apples
3 kg bananas
I don't know how many Bananas the person buys how I work that out?
OT: how long has Ackbeet been green?!