It is not a tough but a little tricky question. here all the in formations are provided for finding the required answer.The person in the question went to have dinner and his bill was 120. He additionally paid a tips of 21.60. Now the thing that needs to be found is the percentage of tips the person leaves behind.
Let us assume that the percentage of tips left behind = x%
Then we can write the equation as:
120 * (x/100) = 21.60
120x/100 = 21.60
12x/10 = 21.60
12x = 21.60 * 10
12x = 216
x = 216/12
= 18
So the person left 18% tips.