The total purchase price of the watch is: $9,300
$8,000 + (0.06 × $8,000) + (0.10 × 8,000) + $20
$8,000 + $480 + $800 + $20
To solve for x, we will begin by using the distributive property
6x - 2(x + 4) = 12
6x - 2x - 8 = 12
(always remember to sort your negatives!)
Add like terms
4x - 8 = 12
Add 8 to both sides
4x = 20
Divide both sides by 4
x = 5