High Jump of 14'; movement is reduced by 10' + jump height/length
Your high jump is pretty straight forward: 7' up with a strength of 18 and the monk using a 10' start. A 3.5 foot vertical leap from a standing start. (How far the bottom of your feet are from the ground at the jump's apex).
While "jump distance doubling" seems to fit the long jump and high jump is measured in "height," assume a ruling where height is doubled so you can high jump 14' with a 10' running start, or 7' with a standing start using step of the wind. (I'd rule favorably on doubling the jump height, since cool monk stuff is cool!)
How high can the monk jump? 14' up if Step of the Wind doubles your high jump.
Your Strength determines how far you can jump.
When you make a high jump you leap into the air a number of feet equal to 3 + your Strength modifier if you move at least 10 feet on foot immediately before the jump. When you make a standing high jump, you can jump only half that distance. Either way, each foot you clear on the jump costs a foot of movement. (Basic Rules, p. 67)
What happens to the movement with Step of the Wind?
Your question appears to mix jumping and movement.
I arrive at a high jump of 14 ft + remaining movement which is rounded
down of 25 ft + extra movement of dash (step of the wind)=+50ft Max
jump = 89 ft?
You used 14 feet of movement, +10 for the running start. 100 -24 = 76 feet of movement left if you want to use it all.
For a running long jump, 10 feet of movement, cover up to 18' (your strength score, doubled to 36' using SoTW). 100 - 46 equals *54 feet of movement left when using step of the wind and dash* after your maxed out running long jump.
When you make a long jump, you cover a number of feet up to your Strength score if you move at least 10 feet on foot immediately before the jump. When you make a standing long jump, you can leap only half that distance. Either way, each foot you clear on the jump costs a foot of movement. (Basic Rules, p. 67)