Let the speed for the first 12 mi be x mi/h, the speed for 18 mi was (x+4) mi/h
thus given that
time=distance/speed
the average time will be:
3=(12+18)/(x+x+4)
3=30/(2x+4)
solving for x we get
3(2x+4)=30
6x+6=30
6x=24
x=4 mi/hr
Answer: 12 mi/hr
Answer: 
Step-by-step explanation:

Hope this helps, have a BLESSED AND WONDERFUL DAY! As well as a great Black History Month and Valentine's day! :-)
- Cutiepatutie ☺❀❤
3/8 times 8/3 = 1
Answer=8/3
There are different ways you can write these numbers all you do is go by what the number says and think about it.
EX1) 12-5=7
EX2) 12-7=5