Step-by-step explanation
then

Step 1
replace A and B

solve for x and y,
isolate y in equation 2 and replace in equation (1)

and replace in equation (1) to get x

so, for the first X, the number are -3 and -3
Step 2

isolate, x in the second equation and replace in the first one

replace in equation

Hence, for the second X, the numbers are 2 and 2
using this method you will be abel to solve all the problems in that page
I hope this helps you