How do I translate this standard form to vertex form? f(x)=-3x^2+20

We are reviewing math from over 18 months ago in pre calc and I am stumped with this problem

1. d.90

2. e. none of these (80)

3. a. 0

4. b. 6

5. e. none of these (10)

6. a. 5

hey! so 1 (25) out of 4 (100) is 25 so your answer is 25%. it's like quarters!

actually your concept is wrong

step-by-step explanation:

150% of x =300

150x=300×100

x=(300×100)÷150

x=200