A force of 20N is pushing a box at an angle of 50 degrees to the right of a dotted line. At what angle would a second force of 40N need to push in order to move the box straight in the direction of the dotted line?

Answer 1

I don't get the picture. Is the dotted line vertical?

Whatever it is, the two components normal to the dotted line must cancel if it is to move in that direction.