4 out of 5 * 8 out of 5 * 9 out of 5 calculation questions, write about the process, thank you!

4 out of 5 * 8 out of 5 * 9 out of 5 calculation questions, write about the process, thank you!

4 / 5 * 5 / 8 * 5 / 9
=1/2*5/9
=5/18

Very simple question. 7-8 / 5-16 / 9-2 / 3 =? (simple operation)
Simple operation is required

In this way
=14-10-9-15
——————
10 16 16 10
=.
How can it be a negative number in the end

A number is five sixths of twenty-three fifths. What is six seventh of this number?

This number is: 23 / 5 × 5 / 6 × 6 / 7 = 23 / 7

Solve the equation: 3 / 4 + χ = 5 / 6 7 χ - 2 / 5 = 5 / 5 how much is the unknown χ?
Solve the equation: 3 / 4 + χ = 5 / 6 7 χ - 2 / 5 = 5 / 5 how much is the unknown χ?
I'm a student party. I haven't learned any textbooks or taught any teachers vulnerable.

Three quarters + χ = five sixths
χ = 5 / 6-3 / 4 = 10 / 12-9 / 12 = 1 / 12
7 χ - two fifths = five fifths
7 χ = two fifths + five fifths = seven fifths
χ = one fifth