Question

The sum of a number times 9 and 19 is at most -21

Answer 1

x multiplied by nine plus 19=(about) -21 so:

9x+19≤-21

Simplify:

9x+19≤-21
9x+19-19≤-21-19
9x≤-40

Thus, your answer is 9x≤-40.

(BTW, you could simplify further, but since -40/9 as some 4's that terminate and repeat, I believe, in this case, you are better off to leave the expression as 9x≤-40.)

ʕ•ᴥ•ʔ