Which algebraic expression represents “the sum of a number and 9”?

x+9

Step-by-step explanation:

the sum is the answer to an addition question

"a number" is a variable (I chose x, but it can be pretty much anything you'd like :)

so, the sum of a number and 9 would be x+9 because you are adding "a number" and 9

  y= -3x is the required function.

step-by-step explanation:

we have been given a table:

x             y

0             0

1             -3

3             -9

-2             6

we can see that the values of y is -3 times the value of x

hence, the function would be: y= -3x.

put the values of x will give the same y as in the table that means function is satisfying the given table.

5   1/4   miles per hour

step-by-step explanation:

15   3/4 / 3 = 5   1/4