1. The problem statement, all variables and given/known data In the figure , the moment of a certain force F is 180ft - lb clockwise about O and 90ft-lb counterclockwise about B. If its moment about A is zero, determine the force. 2. Relevant equations Moment of a force Mo = Fy(x) Mo = Fx(y) 3. The attempt at a solution Since its moment about A is zero then the force passes through A down to the right because the problem mentioned its directions: Moment of F w/ respect to O = 180ft - lb = Fx(y) 180ft - lb = Fx (3) Fx = 30lb Moment of F w/ respect to B = 90ft - lb = Fy(x) 90ft - lb = Fy(6) Fy = 15lb using Summation of components: F^2 = (30)^2 + (15)^2 F = 61.8lb the answer at the book is 75lb down to the right at theta = 36.9 degrees is the book a typo?