Answer: yes
Here, we want to decide if 15 is a solution for the equation 4b - 20 = 40. We can do this by simply plugging in 15 for b. If the statement holds true when 15 is plugged in for b, then 15 is a solution.
Plugging in 15 for b, we have 4(15) - 20 = 40.
4(15) is equal to 60.
So we have 60 - 20 = 40 or 40 = 40.
Since the statement holds true, yes,
15 is a solution for the equation.