Question

If y=kx, where k is a constant, and y=24 when x=6, what is the value of y when x=5?

Answer choices:
A) `-6x-5`
B) `6x+5`
C) `6x-5`
D) `6x^2-15x`

I keep getting `y=20`, but it's none of these choices

Answer 1

You're right

Explanation:

Solving for k,
y = kx
24 = k(6)
k = 4

Substitute in k and given x,
y = 4x = 4(5) = 20

Option A: `-6(5) - 5 = -35`
Option B: `6(5) + 5 = 35`
Option C: `6(5) - 5 = 25`
Option D: `6(5)^2 - 15(5) = 75`

None of the options is equal to 20 when x = 5.