Question 186843
Can anyone help solve each system by the addition method? 
3/7x+5/9y=27
1/9x+2/7y=7
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3x-2.5y=7.125
2.5x-3y=7.3125
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Thanks so much!!
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You just need to get rid of the fractions in the first
and get rid of the decimals in the second.

{{{system((3/7)x+(5/9)y=27, (1/9)x+(2/7)y=7)}}}

Multiply the first equation through by the LCD of 63.
Multiply the second equation through by its LCD, which just
happens to be 63 also.

{{{system(63*(3/7)x+63*(5/9)y=63*27, 63*(1/9)x+63*(2/7)y=63*7)}}}

That becomes

{{{system(27x+35y=1701,7x+18y=441)}}}

Can you solve that? If not post again asking how.

Answers: x=63, y=0

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{{{system(3x-2.5y=7.125,2.5x-3y=7.3125)}}}

Get rid of the decimals by multiplying through by 10000

{{{system(30000x-25000y=71250,25000x-30000y=73125)}}}

You can divide the first one through by 1250 and the
second one through by 625:

{{{system(24x-20y=57,40x-48y=117)}}}

Can you solve that? If not post again asking how.

Answers: {{{x=9/8}}}, {{{y=-3/2}}}

Edwin</pre>