Answer :
in 1 hour ther are 60 minute so
1/2 hour=30 minutes
so 30 times 70=resting beats per 1/2 hour=2100
then 150 times 30=jogging beats per minute=4500
subtract
4500-2100=2400
it beat 2400 more times
1/2 hour=30 minutes
so 30 times 70=resting beats per 1/2 hour=2100
then 150 times 30=jogging beats per minute=4500
subtract
4500-2100=2400
it beat 2400 more times