The formula for Ohm's Law is RI=E, where E represents the voltage measured in volts, I represents the current measured in amperes, and R represents resistance
measured in ohms. Which of the follow equations could be used to solve for R?

Red paint needed = x = 17.5 ounces

Step-by-step explanation:

Ratio of red to blue paint = 5 ounces : 6 ounces

If she has 21 ounces of blue paint, how much red paint will she need?

Ratio of red to blue paint = x ounces : 21 ounces

Equate the ratios

5 : 6 = x : 21

5/6 = x/21

Cross multiply

5*21 = 6*x

105 = 6x

x = 105/6

x = 17.5 ounces

Red paint needed = x = 17.5 ounces