how do i solve systems of three equations with elimination??
Look for the variable that has the "easiest" coefficients.
take any two equations, by multiplying by suitable constants, get the coefficients of one variable to be the same, then subtract the two equations.
take any other pair and by targeting the SAME VARIABLE, multiply by a suitable constant to get the coefficients the same, then subtract the two equations.
You now have 2 equations in the same two variables.
Solve these using the standard grade 9 way of solving two equations in 2 variables that you know.
Once you found the solution to these two variables, backsubstitute in the easiest of the original equations to find the third variable.