Let the number be x and so the expression is: x-19
It can be: x-7
-10-18x
It can be: 7-4x as an algebraic expression
If x is the unknown variable then it can be: x-16
(5 - x) - 7
11-n
As an expression it is: x-6
x-(x+4)
17 - y
15-X
It can be: x-7
5-x=2
a number decreased by 1
the + of a number and 10 k decreased by 4 = k-4
r/2-8
18 - 3n
-10-18x