Question 203932
36.) 
3/7x + 5/9y=27
1/9x + 2/7y=7 
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Eliminate fractions.  Multiply both eqns by 63.
27x + 35y = 1701
7x + 18y = 441
To solve by "addition" (actually, it's elimination using addition) get one of the variables to have the same coefficient, either the x's or the y's.
Multiply the 1st eqn by 7 and the 2nd by -27.
189x + 245y = 11907
-189x - 486y = -11907
--------------------- Add them
0x - 243y = 0
y = 0
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x = 63
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44.) 
3x-2.5y=7.125
2.5x-3y=7.3125
Multiply both eqns by 16
48x - 40y = 114
40x - 48y = 117
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Multiply eqn 1 by 5 and eqn 2 by -6
240x - 200y = 570
-240x + 288y = -702
------------------- Add them
0x - 88y = -132
y = 1.5
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x = 3.625