mom rids 75 km in 50 minwat is her middelt fast per our

I believe you want to know the hourly rate.

Note that 75km/ 50 min  = 1.5km/min

So, since there are 60 minutes in an hour, take this rate and multiply it by 60.

So we have.....

1.5km/min * 60min   = 90 km........so....she travels 90km/hr