Question 772783
The equation for simple interest calculation is 
S.I. = (P * R * T)/100
where S.I. = simple interest
      P = principal amount
      R = rate of interest in percentage
      T = time in years 
  '*' symbol denotes multiplication
 
Therefore according to the problem
    270 = (1200 * 5 * T)/100
or  270 * 100 = 6000T
or  T = 27000/6000 = 4.5yrs
 
So the required time to get $270 as simple interest on $1200 @ 5%is 4years and 6months.