To determine the input number, we can use the following steps:
Calculate the change in the input number as a percentage of the input number. In this case, the input number decreased by 15%, so the change is -0.15 * input number.
Add the change to the output number to find the input number. In this case, the output number is 50, so the input number is 50 + (-0.15 * input number).
Solve for the input number. In this case, we can solve for the input number by rearranging the equation and solving for x:
input number = 50 / (1 - 0.15)
input number = 50 / 0.85
input number = 58.82
Therefore, the input number is 58.82.
Note that this process can also be used to determine the output number given the input number and the percentage change. For example, if the input number is 100 and it increases by 85%, the output number would be:
output number = 100 * (1 + 0.85)
output number = 100 * 1.85
output number = 185