Question 140483
(63/6)(48/7)
You have to mentally or on paper factor the numbers.

= (7*3^2/2*3)(3*4^2/7)

Then you have to find factors that are common to numerator and denominator
like 3 and 7; cancel these because (3/3)= 1 and 7/7 = 1
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= (3/2)(3*2^4/1)

If you missed some common factor on the 1st go round do it again.
Cancel the common "2" that is in the numerator and the denominator:

= (3/1)(3*2^3/1)

When there is no more canceling to do, simplify the result:

= 9*8 = 72
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Cheers,
Stan H.