To find the answer you have to find the bpm of each time that Chandra recorded her heart rate. So when she recorded her heart rate when running, you simply divide 1850 by 15, and you should get 123.333 (repeating) I am assuming by the answers that we are rounding, so we are going to round that answer up. Next to find her heart rate while resting, you take her heart rate in 30 seconds, which is 36, and multiply it by 2, because it was her heart rate in half of the time that we are measuring it in. So when you multiply 36 by 2 you should get 72. The next step is to subtract 124 from 72. You answer is 52.
