The answer I think it would be -6 right?
Try and get the variable by its self by -81 from both sides then divide it by 7 and get ur answer.
Number three is D and number 4 is also D.
Explanation for number three:
When you divide 12 by 3, you get 4. This gives us the number we need to multiply 10 by to get our answer. 10 x 4 = 40
Explanation for number 4:
In the last question, the first step to getting to the answer was to divide the first two numbers. This is no different. When you divide 32.5 by 5, you get 6.5. Then you multiply 10 and 6.5, which equals 65.
To start, find your equation, n=3000(.5)^t, n being your number of bacteria and t being your time. Now plug in 375 for n and solve for t, 375=3000(.5)^t, .125=.5^t,

. This means your answer is 3 minutes. To check it, plug it into your equation. n=3000(.5)^t=3000(.125)=375