Which ordered pair is the best estimate of the solution of the system 3x+y=4 x-3y=4?

Given a(-12,5) and b(12,29) find the point that divides the line segment ab three-eighths of the way from a to b

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%.

Anyone know? will mark brainliest if correct