84=16a-4

Rewrite the equation as 16a-4=84.

16a-4=84

Divide 8 by 4.

16a-4=2

Multiply each term by a-4 and simplify.

Multiply each term in 16a-4=2 by a-4.

16a-4⋅(a-4)=2⋅(a-4)

Cancel the common factor of a-4.

Cancel the common factor.

16a-4⋅(a-4)=2⋅(a-4)

Rewrite the expression.

16=2⋅(a-4)

16=2⋅(a-4)

Simplify 2⋅(a-4).

Apply the distributive property.

16=2a+2⋅-4

Multiply 2 by -4.

16=2a-8

16=2a-8

16=2a-8

Rewrite the equation as 2a-8=16.

2a-8=16

Move all terms not containing a to the right side of the equation.

Add 8 to both sides of the equation.

2a=16+8

Add 16 and 8.

2a=24

2a=24

Divide each term by 2 and simplify.

Divide each term in 2a=24 by 2.

2a2=242

Cancel the common factor of 2.

Cancel the common factor.

2a2=242

Divide a by 1.

a=242

a=242

Divide 24 by 2.

a=12

a=12

a=12

Solve for a 8/4=16/(a-4)