The numbers on the right column follows the following formula
Therefore, the number on the right column for question 3 is also on this format. 150 is equal to this expression for some given n, to find this value of n we just need to estabilish an equality between 150 and the expression.
Solving this expression for n, we have
And this give to us the n value, that is also the value for the left column. The answer for question 3 is 180.