The table shows the rates charged for the use of electricity in a country.

1. Glen and his family used 20 units of electricity in April. How much did they pay for the usage of electricity in April?
2. Joelle and her family paid $155.60 for the usage of electricity in May. How many units of electricity did they use in May?

(a)
Amount that Glen and his family paid for the usage of electricity
= 20 x 0.82
= $16.40

(b)
Amount that Joelle and her family paid for first 30 units of electricity
= 30 x 0.82
= $24.60

Amount that Joelle and her family paid for next 30 units of electricity
= 30 x 1.59
= $47.70

Amount that Joelle and her family paid for the remaining units of electricity
= 155.60 - 24.60 - 47.70
= $83.30

Remaining units of electricity that Joelle and her family used
= 83.30 ÷ 2.38
= 35

Total number of units of electricity that Joelle and her family used
= 30 + 30 + 35
= 95

Answer(s): (a) $16.40; (b) 95