Posted by **Alex** on Saturday, January 30, 2010 at 1:49pm.

i need help with this problem x AND y ARE THE SAME IN BOTH PROBLEM????

7x+8y=25

9x+10Y=35

- math -
**Damon**, Saturday, January 30, 2010 at 4:05pm
7x+8y=25 times 5 is 35 x + 40 y = 125

9x+10y=35 times 4 is 36 x + 40 y = 140

++++++++++++++++++++++now subtract

-1 x + 0 = -15

so

x = 15

then

7(15) + 8 y = 25

105 + 8 y = 25

8 y = -80

y = -10

- math -
**Alex**, Saturday, January 30, 2010 at 4:22pm
thanks but y\why did you multiply it by 4 and 5 at the begging

- math -
**Damon**, Saturday, January 30, 2010 at 6:19pm
Because 40 is the least common multiple of 8 and 10

I could have used the first times 9 and the second times 7 and eliminated x.

- math -
**Anonymous**, Wednesday, April 13, 2011 at 4:28am
What method is this (like is it elimination,substiution)

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