SOLUTION: evaluate the expression 7/8 - 4/9 leave in fractional form

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Question 105304: evaluate the expression
7/8 - 4/9
leave in fractional form
Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!
Solved by pluggable solver: Fractions Solver


7%2F8-4%2F9 Start with the given expression




In order to subtract these two fractions, these fractions need to have a common denominator.


In order to do that, we simply find that the LCM of 8 and 9 is 72 (note: if you need help with finding the LCM, check out this solver)


Now we need to get each denominator to 72



%289%2F9%29%287%2F8%29-4%2F9 Multiply 7%2F8 by %289%2F9%29


63%2F72-4%2F9 Multiply 7%2F8 and %289%2F9%29 to get 63%2F72



63%2F72-%288%2F8%29%284%2F9%29 Multiply 4%2F9 by %288%2F8%29


63%2F72-32%2F72 Multiply 4%2F9 and %288%2F8%29 to get 32%2F72



Since both fractions have a common denominator of 72, we can now combine the fractions


%2863-32%29%2F72 Combine the fractions


31%2F72 Subtract the numerators



So

7%2F8-4%2F9=31%2F72