20. A shop sign says, "T-shirts. Three for the price of two. Equivalent to a saving of $£ 5.50$ on each T-shirt." Using this special offer, what is the cost of three T-shirts?
A $£ 16.50$
B $£ 22$
C $£ 31$
D $£ 33$
E $£ 49.50$
20. D As buying three T-shirts for the price of two is equivalent to a saving of $£ 5.50$ on each T-shirt, the money saved using this offer is $3 \times £ 5.50=£ 16.50$. The money saved is the cost of one T-shirt so this cost is $£ 16.50$.
So, using the offer, the cost of three T-shirts is $2 \times £ 16.50=£ 33.00$.