Ivy’s father wanted to keep track of the gas he purchased for 3 weeks. he purchased 22.5 gallons during the first week and 19.71 gallons the second week. he forgot to write down his purchases for week 3. he knows he purchased a total of 61.75 gallons during the 3 weeks. how much gas did ivy’s father purchase during week 3? gal

Total amount of gas purchased by Ivy's father in the first week = 22.5 gallons
total amount of gas purchased by Ivy's father in the second week = 19.71 gallons
Let us assume the amount of gas purchased by Ivy's father in the third week = x
The total quantity of gas purchased in 3 weeks by Ivy's father = 61.75 gallons
Then
22.5 + 19.71 + x = 61.75
42.21 + x = 61.75
x = 61.75 - 42.21
   = 19.54 gallons
So 19.54 gallons of gas was bought by Ivy's father in the third week

If you would like to know how much gas did Ivy's father purchase during the third week, you can calculate this using the following steps:

22.5 gallons + 19.71 gallons + n = 61.75 gallons
n = 61.75 - 22.5 - 19.71
n = 19.54 gallons

Result: Ivy's father purchased 19.54 gallons during the third week.