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

Destination	Letters		Postcards
	Mass	Postage Rate	Per piece
Thailand, Vietnam, Myanmar	1st 40 g	$1.50	$0.70
	Every additional 10 g or part thereof	$0.45

How much did Gwen pay for the postage when she sent a letter which weighed 105 g and 5 postcards to Vietnam by airmail?
Remaining mass that Gwen had to pay for the letter as it was more than 40 g
= 105 - 40
= 65 g

Number of sets of additional 10 g of the letter that Gwen had to pay for 
= 65 ÷ 10
= 6 r 5

Total number of sets of additional 10 g of the letter that Gwen had to pay for 
= 6 + 1
= 7

Amount that Gwen had to pay for the sets of additional 10 g of the letter
= 7 x 0.45
= $3.15

Total amount that Gwen had to pay for the letter
= 1.50 + 3.15
= $4.65

Amount that Gwen had to pay for the 5 postcards
= 5 x 0.70
= $3.50

Total amount that Gwen paid
= 4.65 + 3.50
= $8.15

Answer(s): $8.15