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 30 g	$1.30	$0.80
	Every additional 10 g or part thereof	$0.35

How much did Roshel pay for the postage when she sent a letter which weighed 66 g and 4 postcards to Vietnam by airmail?
Remaining mass that Roshel had to pay for the letter as it was more than 30 g
= 66 - 30
= 36 g

Number of sets of additional 10 g of the letter that Roshel had to pay for 
= 36 ÷ 10
= 3 r 6

Total number of sets of additional 10 g of the letter that Roshel had to pay for 
= 3 + 1
= 4

Amount that Roshel had to pay for the sets of additional 10 g of the letter
= 4 x 0.35
= $1.40

Total amount that Roshel had to pay for the letter
= 1.30 + 1.40
= $2.70

Amount that Roshel had to pay for the 4 postcards
= 4 x 0.80
= $3.20

Total amount that Roshel paid
= 2.70 + 3.20
= $5.90

Answer(s): $5.90