SOLUTION: Solve and check. 4/x = 5/7

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Question 54212: Solve and check.
4/x = 5/7
Answer by funmath(2873) About Me  (Show Source):
You can put this solution on YOUR website!
You could cross multiply, but that's hard to show by computer. Ask someone to show you that in person. Another way to do it is to multiply both sides of the equal sign by the LCD (lowest common denominator).
4%2Fx=5%2F7 The LCD is 7x.
7x%2A%284%2Fx%29=7x%2A%285%2F7%29
7%2A4x%2Fx=7%2A5%2Ax%2F7
7%2A4%2Across%28x%29%2Fcross%28x%29=cross%287%29%2A5%2Ax%2Fcross%287%29
28=5x
28%2F5=5x%2F5
highlight%28x=28%2F5%29
Check by substituting x=28/5 into the original equation, simplify, and see if both sides equal.
4%2F%2828%2F5%29=5%2F7 When dividing by a fraction multiply by the reciprocal.
4%2A%285%2F28%29=5%2F7
%2820%2F28%29=5%2F7
4%2A5%2F%284%2A7%29=5%2F7
5%2F7=5%2F7
We're right!
Happy Calculating!!!