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

Destination	Letters		Postcards
	Mass	Postage Rate	Per piece
New Zealand, Australia	1st 30 g	$0.80	$0.70
	Every additional 10 g or part thereof	$0.45

How much did Emma pay for the postage when she sent a letter which weighed 55 g and 3 postcards to New Zealand by airmail?
Remaining mass that Emma had to pay for the letter as it was more than 30 g
= 55 - 30
= 25 g

Number of sets of additional 10 g of the letter that Emma had to pay for 
= 25 ÷ 10
= 2 r 5

Total number of sets of additional 10 g of the letter that Emma had to pay for 
= 2 + 1
= 3

Amount that Emma had to pay for the sets of additional 10 g of the letter
= 3 x 0.45
= $1.35

Total amount that Emma had to pay for the letter
= 0.80 + 1.35
= $2.15

Amount that Emma had to pay for the 3 postcards
= 3 x 0.70
= $2.10

Total amount that Emma paid
= 2.15 + 2.10
= $4.25

Answer(s): $4.25