Answer
$(a)\space F_{A}-F_{B}=142\space N\space and \space \theta=67^{\circ}$ south of east.
$(b)\space F_{B}-F_{A}=142\space N\space and \space \theta=67^{\circ}$ north of west.
Work Step by Step
Please see the attached image first.
The image consists of two scalar diagrams, and we can measure the magnitude, and direction of the resultant force by using the meter rule, and protractor.
(a) From figure (1) we can get,
$F_{A}-F_{B}=142\space N,\space \theta=67^{\circ}$ south of east.
(b) From figure (2) we can get,
$F_{B}-F_{A}=142\space N,\space \theta=67^{\circ}$ north of west.
