How can I figure out...

Algorithms and data examples to be written:

Problem $1$: $($Hint: Use a sequential structure$)$

How do you calculate the miles you are getting per gallon of gasoline if you record the mileage reading from your car's odometer each time you fill up the gas tank? Two odometer readings should be inputted, one reading is before you fill up the gas tank, and the second reading is when you refill the ga tank$.$ The third input is the quantity of gallons of gasoline purchased when the gas tank is refilled. Afte inputting these $3$ values, calculate and output:

a$.$ The miles traveled between gas refills

b$.$ The average miles per gallon based on the miles traveled and the amount of gasoline purchased after the time the gas tank is refilled

Algorithm:

Input