Mr. mcdonald offers the tractor salesman $2000 for a used tractor. this offer includes 6% sales tax. if the salesman accepts the offer, what is the cost of the tractor, before tax

The salesman will get $1,880 with out the 6% tax

For this problem we must backtrack, and deduct the sales tax!
So lets make an equation to solve.
original price = final price / ( 1 + sales tax rate)  so

op = 2000 / 1.06 = 1886.80

lets see if this is correct!

1886.80 * 0.06 = 113.208  <- tax

1886.80 + 113.208 = 2000