Step-by-step explanation:
Option 1.
4y=12
Dividing 4 both sides
y=3
Division property should be used.
Option 2.

Cross multiplying each other,
y=12(4)
y=48
Option 3.
2(4y)=12
Opening bracktet in LHS
8y=12
Dividing both sides by 8 i.e.

Division property is used.
Option 4.
y+4=12
Subtracting both sides by 4 i.e.
Y+4-4=12-4
y=8
Subtraction property is used.
It means that in option (4) Soo-Jung used the subtraction property of equality to solve an equation for y.