Answer:
a)
x = (158-112) / 1x
or 158-112 / x
b) 112+ 23 /158-23 = x
or if you want x to be the same value as the first part then you could write
112+x / 158-x = 135/135
or revise as an equality
23 ≤ 112 < 158
112 + 23 = 158
112 + x = 158
Explanation:
Tailwind speed
x = 158-112 / 2
x = 46/2
x = 23 knots
Speed
x = 112 + 23 / 158-23
x = 135 / 135 m/h = same speed as stated in question.