Slide 2:
Formula for a 2 x 2 system:
Given a1x + b1y = c1
a2x + b2y = c2
Slide 3:
Formula for a 3 x 3 system:
Given a1x + b1y +c1z = d1
a2x +b2y + c2z = d2
a3x + b3y + c3z = d3
Slide 4:
You will notice that all the denominators are the same. When you are finding x, replace the x coefficients with the constants, when you are finding y, replace the y coefficients with the constants, and when you are finding z, replace the z coefficients with the constants.