1) Solve the first equation for either variable.
2) Every where in the second equation that the solved-for variable appears, replace it with the value it is equal to.
3) You now have only 1 variable in the second equation. Solve the second equation for that variable and you will get a numeric value for it.
4) Every where in either of the original equations that the variable you just found a numeric value for exists, plug in the numeric value instead.
5) You can now solve that equation for the other variable, obtaining a numeric value for it also.
Solve by Substitution method.
15x-20y=-7
15y=4+5x
2 answers
5x-15y=4
2 answers