Please help me, I just need a refresher on the method to finding the answer.

Thanks!

2.5%

Step-by-step explanation:

part over whole = part over whole

0.5/20 = p/100

then cross multiply

(0.5)(100) = 20p

50 = 20p

then divide both sides by 20

2.5 = p

To check, change 2.5% to a decimal by dividing by 100, (=0.025) then multiply by 20.

20 x 0.025 = 0.5

225x²+4=0

225x²=0-4

225x²=-4

x²=-4/225

x=±√-4/225