PSLE The airmail rates to two countries are shown. Barbara sent a letter weighing 71g to Laos and a letter weighing 31g to China by airmail. How much did she pay altogether?
Mass |
Laos |
China |
First 40g |
$0.65 |
$1.50 |
Every additional 20g |
$0.35 |
$0.55 |
Mass of the letter to Laos excluding the first 40 g
= 71 - 40
= 31 g
Sets of additional 20 g of the letter to Laos
= 31 ÷ 20
= 1 r 11
Sets of additional 20 g and part thereof the letter to Laos
= 1 + 1
= 2
Amount that Barbara paid for the letter to Laos
= 0.65 + 2 x 0.35
= 0.65 + 0.70
= $1.35
Amount that Barbara paid altogether
= 1.35 + 1.50
= $2.85
Answer(s): $2.85