233 A force creating counterclockwise and clockwise moments

Problem 233
In Fig. P-231, a force P intersects the X axis at 4 ft to the right of O. If its moment about A is 170 ft·lb counterclockwise and its moment about B is 40 ft·lb clockwise, determine its y intercept.
 

Three points in XY plane (A, B, and O)

 

Solution 233