The table shows the airmail rates for sending letters and postcards to some countries.

Destination	Letters		Postcards
	Mass	Postage Rate	Per piece
Indonesia, Malaysia	1st 20 g	$0.80	$0.80
	Every additional 10 g or part thereof	$0.45

How much did Abi pay for the postage when she sent a letter which weighed 79 g and 2 postcards to Malaysia by airmail?
Remaining mass that Abi had to pay for the letter as it was more than 20 g
= 79 - 20
= 59 g

Number of sets of additional 10 g of the letter that Abi had to pay for 
= 59 ÷ 10
= 5 r 9

Total number of sets of additional 10 g of the letter that Abi had to pay for 
= 5 + 1
= 6

Amount that Abi had to pay for the sets of additional 10 g of the letter
= 6 x 0.45
= $2.70

Total amount that Abi had to pay for the letter
= 0.80 + 2.70
= $3.50

Amount that Abi had to pay for the 2 postcards
= 2 x 0.80
= $1.60

Total amount that Abi paid
= 3.50 + 1.60
= $5.10

Answer(s): $5.10