How to Cross Multiply

Step-by-Step Guide

1. 1

   Step 1: Multiply the numerator of the left-hand fraction by the denominator of the right-hand fraction.

   Let's say you're working with the equation 2/x = 10/13.
   
   Now, multiply 2 *
   13. 2 * 13 =
   26.
2. 2

   Step 2: Multiply the numerator of the right-hand fraction by the denominator of the left-hand fraction.

   Now multiply x by
   10. x * 10 = 10x.
   
   You can cross multiply in this direction first; it really doesn't matter as long as you multiply both numerators by the denominators diagonal from them. , Just set 26 equal to 10x. 26 = 10x.
   
   It doesn't matter which number you list first; since they're equal, you can swap them from one side of the equation to the other with impunity, as long as you treat each term as a whole.
   
   So, if you're trying to solve 2/x = 10/13 for x, you'd have 2 * 13 = x * 10, or 26 = 10x. , Now that you're working with 26 = 10x, you can start by finding a common denominator and dividing both 26 and 10 by a number that divides evenly into both numbers.
   
   Since they are both even, you can divide them by 2; 26/2 = 13 and 10/2 =
   5.
   
   You're left with 13 = 5x.
   
   Now, to isolate x, divide both sides of the equation by
   5.
   
   So, 13/5 = 5/5, or 13/5 = x.
   
   If you'd like the answer in decimal form, you can start by dividing both sides of the equation by 10 to get 26/10 = 10/10, or
   2.6 = x.
3. 3

   Step 3: Set the two products equal to each other.

4. 4

   Step 4: Solve for the variable.

Detailed Guide

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