Answer :
Let the cost of the computer be x
6% of x + x = $1,086.50
6x/100 + x = $1,086.50
0.06x + x = $1,086.50
1.06x = $1,086.50
Divide both-side of the equation by 1.06
1.06x /1.06 = $1,086.50/1.06
x = $1025
Therefore the cost of the computer before sale tax = $1025