Answer:
11/40 of a gallon
Step-by-step explanation:
The amount of gasoline in the tank of lawn mower = 3/8 of a gallon
Then he put the amount of gasoline in the tank = 4/10 of a gallon
The total amount of gasoline filled in the tank = 3/8 + 4/10
= 3/8 + 2/5
= 15+16/40
= 31/40
The total amount of gasoline filled in the tank = 31/40
The amount of gasoline left in the tank after mowing = 2/4
Total amount of gasoline Michael used = 31/40 - 2/4
= 31-20/40
= 11/40 of a gallon
Alternatively, you can follow this method:
Total amount of gasoline Michael used = 3/8 + (4/10 - 2/4)
= 3/8 + (2/5 - 2/4)
= 3/8 + ( 8-10/20)
= 3/8 + (-2/20)
= 3/8 + (-1/10)
= 3/8 - 1/10
= 30-8/80
= 22/80
= 11/40 of a gallon
Total amount of gasoline Michael used = 11/40 of a gallon
