The ratio is 1:3, meaning Jane has 3x more money than Peter. Or, Peter has 1/3 as much money as Jane. You know that Jane has 12 dollars more than Peter so you can think of scenarios. Because it is a 1/3 the answer for Peters money has to be 1/3 of Janes, so Peter has 6 dollars, and Jane has 12 more, so Jane has 18 dollars.
