The answer is 56.73 because you're basically just getting 30.5 and adding it to its 86%. You take 30.5 and multiply it by 1.86 which gives you 56.73. If you are still confused, you multiply it by a decimal because ultimately, decimals are just a way for people to think of as the numbers between 0 and 1. When they say what's 10% of something, they mean the 1/10 of that number, in other words, 0.1.