Question 156676
I'll do the first two to get you started


# 1


{{{2xy + 1 = xy + 3}}} Start with the given equation



{{{2xy + 1 - xy = 3}}} Subtract {{{xy}}} from both sides



{{{2xy - xy = 2}}} Subtract {{{1}}} from both sides



{{{xy = 2}}} Combine like terms.



{{{y=2/x}}} Divide both sides by {{{x}}} to solve for {{{y}}}


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Answer:


So the solution is {{{y=2/x}}} 


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# 2





{{{(3/4)x+(4/7)y=(5/4)x-1}}} Start with the given equation.



{{{28((3/cross(4))x+(4/cross(7))y)=28((5/cross(4))x-1)}}} Multiply both sides by the LCD {{{28}}} to clear any fractions.



{{{21x+16y=35x-28}}} Distribute and multiply.



{{{16y=35x-28-21x}}} Subtract {{{21x}}} from both sides.



{{{16y=14x-28}}} Combine like terms on the right side.



{{{y=(14x-28)/(16)}}} Divide both sides by {{{16}}} to isolate {{{y}}}.



{{{y=(14x)/(16)-(28)/(16)}}} Break up the fraction



{{{y=(7/8)x-7/4}}} Reduce


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Answer:


So the solution  is {{{y=(7/8)x-7/4}}}