0>= (5-x)/2 >=-10
1) We have the following 2 conditions:
[1]: 0 ≥ 5 -x2
[2]: 5 -x2 ≥ -10
2) Let's solve for x: 0 ≥ 5 -x2 [1]
⇥The expression 5 -x is zero at:
⇥ x = 5
⇥Its coefficient of x, -1, being negative, it is positive before and negative after 5
Solution obtained [1]: x ≥ 5
3) Let's solve for x: 5 -x2 ≥ -10 [2] where x ≥ 5
5 -x2 ≥ -10
5 -x ≥ -10·2
ⓘ A single minus sign does not cancel out, the product of a negative number by a positive number is negative: -10·2 = -20
5 -x ≥ -20
ⓘ We gather the terms in x on the right and the other terms on the left
5 + 20 ≥ x
ⓘ Start from 5 and move forward 20 on the number line: 5 + 20 = 25
25 ≥ x
Solution found [2]: x ≤ 25
Intersecting x ≥ 5 and x ≤ 25 gives x ∈ [5, 25]
▶Solution:   x ∈ [5, 25]