How to solve proportion problems. I'm Bon Crowder with MathFour.com and we're going to talk about proportion problems. Here we have one. Bon and Kate have apples in the proportion of 1 to 3. Bon, that's me, has 5 apples. How many apples does Kate have? Well the proportion 1 to 3 means 1/3 so this is how many Bon has to how many Kate has. So we know that Bon has 5 apples for real, not in proportion. So the question is how many does Kate have. So we put these two fractions together and we say 1/3 = 5/how many? And sometimes when we mean how many instead of a ? we use a variable. So what we do is we multiply both sides by X/1 and then we have X/3 = 5X because the Xs cancel and then we multiply both sides by 3 and then the 3s cancel and then we have X = 15. Let me go ahead and cancel those 3s. And I have X = 15. And what is 15, 15 is how many apples Kate has. And that's how you solve a proportion problem. I'm Bon Crowder with MathFour.com. Have fun solving proportions.