1.) Divide 92 by 100 so that it can be 100 pieces or 100% 92/100= 0.92
2.) Multiply the 15% be 0.92 to get how much more inches in snow that they got this year than last year. 15 X 0.92= 13.8
3.) Since we have how much more inches of snow they got all we need to do is subtract 13.8 from 92. 92-13.8= 78.2
4.) In the previous year the town had received 78.2in of snow.
I hope this helps :)