If y varies directly as x and y = 3 when x = 24, find y when x = -16

Adepartment store purchases screen-printed t-shirts at a cost of $5 per shirt. they mark up the price 150% (making the selling price 250% of the store's purchase price) and put them on the sales floor. every month that a t-shirt doesn't sell, the store reduces the selling price by 25%.

Can someone me and do the problem plz so i can understand it more better

What is the value of n in the equation -1/2(2n+4)+6=-9+4(2n+1)