Consider the system of equations. −8x+4y=0−8x+7y=6 which property could be used to write the equation −3y=−6 as the first step to solving the system of equations? subtraction property of equality distributive property of equality substitution property of equality division property of equality

We know that
The subtraction property of equality tells us that if we subtract from one side of an equation, we also must subtract from the other side of the equation to keep the equation the same

that means

if a=b  and  c=d
a-c=b-d

then 
−8x+4y=0> equation 1
a=(-8x+4y)    b=0

−8x+7y=6> equation 2
c=(-8x+7y)   d=6

therefore

(-8x+4y)-(-8x+7y)=0-6
-8x+4y+8x-7y=-6
-3y=-6

the answer is the option 
Subtraction Property of Equality

I'm sure the answer is a