the body is undergoing rotational motion about the origin i.e. it is rotating in a circle having its centre as the origin and the radius is equal to the distance of that point from the origin. the distance of the given line from origin is 4/square root2

now the angular momentum can be calculated easily by putting the values

see one can calculate da angular momentum undergoing linear motion from da origin......nw u draw da coordinate axes and draw da line u ll find dat da prependicular distance of da origin to the line is 4/V2......

 y = x+4               (given)

 x-y+4 = 0

perpendicular distance from origen = 4/sqrt2=2sqrt2 m

now angular momentam = mvr                           (r is the perpendicular distance of line of motion of particle                                                                      & point about which we have  to calculate angular momentam)

                                 =5*(3sqrt2)2sqrt2

                                 =5*3*4

                                 =60