Question

Joseph removes 5/8 gallons of white paint from a can. Then he adds 5/8 gallons of blue paint to the can.

Write and then evaluate a subtraction expression to find the overall increase or decrease in the amount of paint in the can.

Answer 1

Answer: Change = - 2.8 gallons

Explanation:

Let X be the starting amount of paint in the can, in gallons.

"Removes 5/8 gallon" can be written -(5/8)gal

"Adds 3/8 gallon" becomes +(3/8)gal

The result is : X - (5/8)gal + (3/8)gal = Remaining Paint (gallons)

Consolidating: Remaining (gallons) = X - (2/8)gal

If we want the overall increase/decrease, subtract the initial volume:

Initial - Remaining = Change in amount of paint in can

Change = (X-(2/8)gal) - X = - (2/8) gallons