Systematic sampling refers to a method of random sampling during which sample members are extracted from a larger population and then collecting corresponding observations using a constant interval between samples taken. This interval, called the sampling interval, is measured by deducting the size of the population by the required sample size. As per the question, the store manager asks every 25th person about the sales which is a classic example of systematic sampling.
You first have to turn 4 2/8 and two and 34/8 and then you have to put one over 64 and multiply cross if there is any corrections to make you just have to simplify and do that