Which equations represent functions?
2x + 3y = 10
4x = 16
2x − 3 = 14
3y = 18
14.6 = 2x

2x + 3y = 10,  3y = 18  (in both cases, for each input x, there is exactly one output y.

Step-by-step explanation:

3y = 10 - 2x, or y = (1/3)(10 - 2x)   Yes, this is a function.

4x = 16 → x = 4        NOT a Function, because for x = 4 there are an infinite number of possible y -values

2x - 3 = 14 →  2x = 17  →  x = 17/2  Not a function.  See reason given above.

3y = 18 →  y = 6   Function

2x = 14.6   →  x = 7.3  Not a function.  See reason given above

|DC| = 9

Step-by-step explanation:

Set up and solve an equation of ratios.  This is possible because the upper and lower triangles are similar.  AB = 10 and DE = 12, so we can write

20      15

=

12      |DC|

Then 20 |DC| =  12(15)  = 180.  Solving for  |DC| :   |DC| = 180/20 = 9