3/10b=2/5 what is b in this equation

Asap 25 pts brainliest to right best/answer

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%.

In which form is the following function written? y = - 2(x – 3)(x + 5)