When solving for percents, I like to use a simple equation
Initial number × (decimal form of the percent) = final number
So, let's use this simple percent equation to solve for the first question
1) 90% of what number is 90?
The decimal form of the percent is 0.9, the final number is 90, and we are solving for the initial number. So,
N (0.9) = 90
N = 100
2) 80% of what number is 80?
The decimal form of the percent is 0.8, the final number is 80, and we are solving for the initial number. So,
N (0.8) = 80
N = 100
3) 274% of what number is 274?
The decimal form of the percent is 2.74, the final number is 274, and we are solving for the initial number. So,
N (2.74) = 274
N = 100
Now the question also asks what the pattern is from these three equations. We can see that the pattern is when you divide by a percent (put into decimal format) that is of the same value as the numerator, you receive 100 as your answer. Pretty cool!