simple intrest what is the intrest for I=54 R=6% and t= 9months

Perhaps you are looking for the principal?

simple intrest what is the intrest for I=54 R=6% and t= 9months

I=Prt

54=P*0.06*9/12

$${\frac{{\mathtt{0.06}}{\mathtt{\,\times\,}}{\mathtt{9}}}{{\mathtt{12}}}} = {\frac{{\mathtt{9}}}{{\mathtt{200}}}} = {\mathtt{0.045}}$$

54=P*0.045

54/0.045 = P

$${\frac{{\mathtt{54}}}{{\mathtt{0.045}}}} = {\mathtt{1\,200}}$$

the principal would have been $1200

I believe that you are missing part of the data. What was the amount of money on which the interest was charged?