Answer:
p = float(input('Principal: '))
r = float(input('Rate: '))
t = float(input('Time: '))
si = (p * r * t) / 100
print(si)
The "float" before the input in the first 3 lines is so you're able to input decimals. If you're not using decimals, you can switch the "float" to "int". However, if you input a decimal number after you switched to int, you will receive an error