Answer:
They are only equal on day 0, both having 10 population.
Step-by-step explanation:
Given the bacteria on the counter is initially measured at 5 and doubles every 3 days we can generate the following geometric equation:

Given the bacteria on the stove is measured at 10 and doubles every 4 days we can create another equation:

To find how many days it will take for the bacteria population to equal the same lets set both equations equal to eachother:

Divide both sides by 10

Since both exponents have the same base we can set the exponents equal to eachother and solve for x:

Multiply both sides by 3 to isolate x on the left side

Multiply both sides by 4 to remove fraction

Subtract 3x to isolate x on the left side

Plug x into one of our original equations

Solve

The correct answer is C!!
Hope this helped!!!
For Ax+By=C, we have y=-3x. We want both the y and x variable on the same side, and that leads us to either subtract y from both sides or add 3x to both sides. You can do either, but I personally prefer the latter, so we have 3x+y=0. We have A=3 (since that is the coefficient for x) and B=1 (since 1*y=y). Lastly, C=0
Feel free to ask further questions!
Here's your answers! Hope this helps.