Establish a plane rectangular coordinate system D-xy with D as the origin, DH as the X axis and DE steering wheel as the positive direction of the Y axis.

Then point coordinates: D (0,0), E (0,2), F( 1, 2), G(3 1), H (3,0), I( 1,-1).

Linear EJ equation: y=2x+2

Direct FG equation: y=- 1/2x+5/2.

Linear IH equation: y= 1/2x-3/2

A( 1/5, 12/5), B(-7/3, -8/3) and C(4, 1/2) are solved by three lines simultaneously.

Get |AB|=√( 1444/45)，|AC|=√(36 1/20)。

∴s(⊿abc)= 1/2*|ab|*|ac|= 1/2*√( 1444/45)*√(36 1/20)= 1/2*36 1/ 15

∴ The paper utilization rate of this scheme = 6/(1/2 * 36115) =180/361.