this is another one yet do i not get? help!

Answer:
Rate of Interest is [tex]20\%[/tex]
Step-by-step explanation:
Given that
[tex]I=\$ 300, P=\$3000[/tex]
and T=0.5 years
To find rate of interest
We have I=PRT
Therefore
[tex]R=\frac{I}{PT}\times 100[/tex]
[tex]R=\frac{300}{(3000)(0.5)}\times 100[/tex]
[tex]=\frac{1}{10(0.5)}\times 100[/tex]
[tex]=20\%[/tex]
Therefore [tex]R=20\%[/tex]
Rate of Interest is [tex]20\%[/tex]