Every 100g of whole meal bread comtains 6g of fibre
a loaf of bread that weighs 800g is cut into 20 equal slices.

how much fibre is there in each slice

Since there is 6g in each 100g of whole meal bread, you would do

6x8=48 and you would do this becuase there is 800g of whole meal bread, which is the same thing as 100g x8 and since there is 6g in each 100, then you would have to times it, to get how much, and now since they slice that in 20 pieces, you would do 48/20=2.4.

So your awnser is: 2.4

a) 15/20 = 3/4

b) 12/20 = 3/5

c) 12/15 = 4/5

d) 10/15 = 2/3

So. It must be answer c).