Solve the following simultaneous equations: x+y=9; x-2y+1=1.

Step 1: x+y=7 can be rearranged as: x= 9 - y.Step 2: We substitute the expression of x in the second equation: 9 - y - 2y + 1 = 1Step 3: We calculate the value of y. 9 + 1 - 1- 3y=0. It is equivalent with: 9 - 3y = 0. So, 9=3y. y=9/3. y=3Step 4: We calculate x. x=9-y ; x= 9-3; x=6Step 5: Checking the values in the given equations. 6 + 3 = 9 (TRUE) 9 - 3 - 6 +1 = 1 ; 1=1 (TRUE)Step 6: x=6 ; y=3