PSLE The airmail rates to two countries are shown. Cathy sent a letter weighing 94g to Laos and a letter weighing 33g to Canada by airmail. How much did she pay altogether?
Mass |
Laos |
Canada |
First 40g |
$0.75 |
$1.30 |
Every additional 20g |
$0.45 |
$0.55 |
Mass of the letter to Laos excluding the first 40 g
= 94 - 40
= 54 g
Sets of additional 20 g of the letter to Laos
= 54 ÷ 20
= 2 r 14
Sets of additional 20 g and part thereof the letter to Laos
= 2 + 1
= 3
Amount that Cathy paid for the letter to Laos
= 0.75 + 3 x 0.45
= 0.75 + 1.35
= $2.10
Amount that Cathy paid altogether
= 2.10 + 1.30
= $3.40
Answer(s): $3.40