Not a particularly "geometric" solution....but see the following image
Let A = (0,4) B = (6, 4) C = (6,0) D = ( 0, 0) E = (2, 4) F = (3,0)
The segment connecting BD has the slope 2/3
And its equation is y = 2/3x
The segment connecting EF has a slope of [ 4 - 0 ] / [ 2 - 3 ] = -4
So....its equation is y = -4(x - 3) ⇒ y = -4x + 12
The x coordinate for P is
(2/3)x = -4x + 12
(2/3)x + 4x = 12
(14/3)x = 12
x = 36/14 = 18/7
And its y coordinate is y = (2/3)(18 7) = 36/21 = 12/7
So.....the base of EBP = 4
And its height is 4 - 12/7 = 16/7
So...its area = (1/2)(4)(16/7) = 32/7
And the area of the rectangle = 6 * 4 = 24
So....the fractional area of EBP to the area of the rectangle is
(32/7) / 24 = 32 / 168 = 4 / 21