elle had $840. she spent 5/12 of the money on some clothes. 7/10 of the money she spent on clothes was used to purchase 4 dresses of the same price how much did each dress cost?

36x2 + 49y2 = 1,764 the foci are located at: (-√13, 0) and (√13,0) (0, -√13) and (0,√13) (-1, 0) and (1, 0)edit: the answer is (- the square root of 13, 0) and (the square root of 13, 0)