<PRE><B>Question 102023</B>
1. x/77x-121y - y/49x-77y

= x/[11(7x-11y)] - y/[7(7x-11y)]
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lcm =  77(7x-11y)
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Write each fraction with lcm as its denominator:
=[x(7) - y(11)]/lcm

= 1/77

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2. a/6a-9b - b/4a-6b

= a/(3(2a-3b)) - b/(2(2a-3b))

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lcm = 6(2a-3b)
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= (2a-3b)/[6(2a-3b)]

= 1/6

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Cheers,
stan H.
</PRE>