This week in math I learned how to solve a system using substitution.
You start with two equations like x+2y=4 and 3x+2y=0. Then you would need to find the equation that looks the easiest to use as a substitution (usually the one with a variable that has a coefficient of one). Then you would rearrange the equation so that only the variable is one one side of the equation. -> x = -2y+4 and 3x+2y=0
Then you would plug in the x into the x in the second equation -> 3(-2y+4)+2y=0
Then simplify it -> -6y+12+2y=0 -> -4y+12=0 -> -4y = -12 -> -4y/-4= -12/-4 -> y=3
Then plug the y into the other equation to find x -> x+2(3)=4 -> x+6=4 -> x=-2
Then plug the x and y into an equation to see if it works : -2+2(3)=4 -> (It works)
Some more examples: