\(F_1=100i-120j+75k\ lb\)
\(F_2=-200i+250j+100k\ lb\)
3D
\(M_0=\vec{R}X\vec{F}\) 
\(F1=100iāˆ’120j+75klb\)
\(R_A=4i+0j+3k\)
\(F2=āˆ’200i+250j+100klb\)
\(R_B=4i+5j+3k\)
\(R_A\ \ X\ \ R_{F1}\)             \(i(0)(75)-(-120)(3)+j(4)(75)-(100)(3)+k(100)(0)-(4)(-120)\)
\(R_A\ X\ \ F_1=\left(360\right)i+\left(480\right)k\)
\(R_{B\ }\ X\ \ F_2=i\left(5\right)\left(100\right)-\left(250\right)\left(3\right)+j\left(4\right)\left(100\right)-\left(-200\right)\left(3\right)+k\left(4\right)\left(250\right)-\left(-200\right)\left(5\right)\)
\(R_A\ X\ F_i=\left(-250\right)i+\left(1000\right)j+\left(2000\right)k\)       
 

Problema 2