The first thing you need to do is find out how much each part is. To do that you need to add each side of the ratio together (3 + 5 = 8). THen you set up an equation showing the 8 parts * x = 48 and solve for x.
8x = 48
x = 6 <-- Value of each part
Now you multiply the 6 by the number on each side of the ratio,
Add the numbers in the ratio together to get 8, and multiply 8 by the variable of x. Divide the total amount of money that both girls earned by 8. You will get x=6. Multiply 6 by 3 to get the amount of money Mary earned, which is 18, and multiply 6 by 5 to get the amount of money Jane earned, which is 30.
