Question 697224
ax+y=c
x+by=d
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abx+by = bc 1st eqn times b
x + by = d
------------ Subtract
x(ab-1) = bc - d
x = (bc-d)/(ab-1)
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ax+ y = c
ax+aby=ad 2nd eqn times a
-------------- subtract
y(ab-1) = ad-c
y = (ad-c)/(ab-1)