Step-by-step explanation:
To determine simple interest, we use the formula

where I is the interest, p is the principal or initial amount, r is the interest rate is in the unit of years and t is the time in years
When the times is 3 years , then we plug in 3 for 't' directly

we know that 1 year = 12 months
Suppose, the time is given in months then we divide time 't' by 12
When the times is 4 months , then we plug in 4 for 't' and divide by 12

we know that 1 year = 365 days
Suppose, the time is given in days then we divide time 't' by 365
When the times is 45 days , then we plug in 45 for 't' and divide by 365
