An appliance store sells only two brands of refigerator. The ratio of the number of brand X refigerators sold at this store to the number of Brand Y refigerators sold is about 4 to 11. Of the next 100 refigerators the store sells, approximately how many will be brand Y? I don't know how to start this one. I wrote 100 = 4x + 11y However, I don't know how to solve a two variable equation.