The sum of two-ninths of a number and 17 is 21

You can write this as an equation. So let n be the number. Two ninths of the number is just (2/9)n, so the equation is...

(2/9)n + 17 = 21

(2/9)n = 21 - 17

(2/9)n = 4

      n = 4/(2/9)

      n = 4 * 9/2

      n = 36/2

      n = 18

So the number is 18.

2,600 divided by 80 = 32.5

step-by-step explanation:

f(2x−x2)=−3x2+6x−1

step-by-step explanation:

set up the composite function and evaluate.

f(2x−x2)=−3x2+6x−1