The information shown here only shows  a principal sum, a rate of interest and a period or time. There is no question  as to what is  needed. But suppose the need is for simple interest, then we calculate using the given information and the formula:
  I = PRT
where I is simple interest, P is the principal, R is the rate  per year, and T is  time
 P = 290, T is 6 months which is 0.5 years,  R = 12.5 % which is written as 0.125 in decimal fraction.
I = 290 × 0.125 x 0.5   →   I = 18.125
Therefore after 6 months , the interest earned will be 18. 125  dollars