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October 20, 2016
Posted by **Sam** on Tuesday, October 12, 2010 at 8:01pm.

3x+5y=21

x=51-9y

- substitution -
**PsyDAG**, Wednesday, October 13, 2010 at 1:32pmSubstitute 51 -9y for x in the first equation and solve for y. Put that value in the second equation to find x. Check by putting both values into the first equation.