W=wind p + w=158...p=158-w p-w=112...p=112+w SO 158-w=112+w 46=2w 23=w SO in conclusion you have the correct answer of wind being 23km/h while the plane is going 135 km/h
1/3 x - 1/2 = 18 1/2 1/3 x = 19 (add 1/2 on the right side to 18 1/2) x = 57 (multiply the reciprocal of 1/3 and that will be 3/1 or 3 to 19 to get x by itself) So, the answer is x = 57 (d. 57)