The answer is 133 beats per minute.
To calculate this, we will use proportion.
If 190 beats per minute are 100%, how many beats per minute are 70%:
190 bpm : 100% = x : 70%



Thus, Xanthe's target heart rate is 133 beats per minute.
I really dont know i am srry
(for x=0) 3 & (for x=4) 19