Question 640232: how do you find x for x/5=7/8??
Answer by josh_jordan(263)   (Show Source):
You can put this solution on YOUR website! To find x, we will use a rule of solving proportions with a variable, which states that we can perform cross-multiplication when dealing with 2 fractions separated by an equal sign:
 = 
In other words, we can multiply the numerator on the left side of the equal sign by the denominator on the right side of the equal sign, and put that answer on the left side. Then, we can multiply the denominator on the left side by the numerator on the right side, and put that answer on the right side of the equal sign. So, with our problem:
 , we would multiply x by 8, put that answer on the left side of the equal sign, then multiply 5 by 7, and put that answer on the right side of the equal sign, resulting in:
Since we want to get x all by itself, we will divide both sides by 8:
 , which leaves us with:
 , which is our final answer in fractional form
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