$1.50C + $4A= $5050
C + A = 2200
-4(C + A = 2200)
-4C - 4A = -8800
1.50C+4A = 5050
-----------------------
-2.5C =- 3750
-2.5C/-2.5 =- 3750/-2.5
C = 1500
C + A = 2200
1500 + A =2200
1500 - 1500 + A = 2200 - 1500
A = 700
CHECK
$1.50C + $4A= $5050
$1.50(1500) + $4(700)= $5050
$2250 +$2800 =$5050
$5050 = $5050
C + A = 2200
1500 + 700 =2200
2200 = 2200
I wish I knew but I’m still in 10th grade
He used it in step 3. The Addition Property of Equality states that whatever you add to one side, you must add the same quantity to the other side. In this case, he added 1/4 to both sides.