Let's find the certain number. According to the problem, we have:
80 divided by the sum of 4 and a certain number (which we'll call x) equals 16.
Let's set up the equation:
80 / (4 + x) = 16
The first step to solve for x is to get rid of the denominator, which is (4 + x). We can do this by multiplying both sides of the equation by the denominator.
Multiplying both sides of the equation by (4 + x), we get:
80 = 16 (4 + x)
Now, we should distribute the 16 on the right side of the equation:
80 = 16 4 + 16 * x
This simplifies to:
80 = 64 + 16x
Next, let's subtract 64 from both sides of the equation to get 16x by itself:
80 - 64 = 16x
16 = 16x
Finally, to solve for x, we divide both sides by 16:
16 / 16 = x
This simplifies to:
1 = x
The certain number that we were trying to find is 1.
Therefore, the answer is (D) 1.
