The diagonals of a rectangle are congruent. We have half of diagonal QO and the whole diagonal of NP. So the equation will look like this: 5x+20=2(3x-4). 5x+20=2(3x-4). 5x + 20 = 6x - 8. 28 = x. Therefore, x = 28 and the length of the diagonals is 160
