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

1. Valen and his family used 45 units of electricity in April. How much did they pay for the usage of electricity in April?
2. Joelle and her family paid $127.30 for the usage of electricity in May. How many units of electricity did they use in May?

(a)
Amount that Valen and his family paid for the usage of electricity
= 45 x 0.77
= $34.65

(b)
Amount that Joelle and her family paid for first 50 units of electricity
= 50 x 0.77
= $38.50

Amount that Joelle and her family paid for next 50 units of electricity
= 50 x 1.29
= $64.50

Amount that Joelle and her family paid for the remaining units of electricity
= 127.30 - 38.50 - 64.50
= $24.30

Remaining units of electricity that Joelle and her family used
= 24.30 ÷ 2.43
= 10

Total number of units of electricity that Joelle and her family used
= 50 + 50 + 10
= 110

Answer(s): (a) $34.65; (b) 110