please help!! will mark as brainliest!

Presley has to clean her 40-gallon fish tank. Her first step is to drain the tank. Using a hose and a
siphon, she finds that she can drain 16 gallons of water per hour.
Presley writes the equation 40 - 16x = 0, where x is the number of hours, to determine how many
hours it will take to drain the tank.
The next step Presley wrote to solve the equation is shown here:
40 = 16x
Which property did she use to get to this step?

a.) addition property of equality
b.) multiplication property of equality
c.) distributive property of equality
d.) combining like terms