By driving 8 mph faster than bob, john can make a 230 mile trip in one half hour less. how fast does bob drive on the trip? round your answer to the nearest mile per hour

  57 mph

Step-by-step explanation:

Let b represent Bob's speed on the trip. Then his time is ...

  time = distance/speed

  Bob's time = 230/b

Then John's speed is b+8, and his time is ...

  John's time = 230/(b+8)

The difference of their times is 1/2 hour:

  Bob's time - John's time = 1/2

  230/b -230/(b+8) = 1/2 . . . substitute the expressions for time

  460(b+8 -b) = b(b+8) . . . . . multiply by 2b(b+8)

  b^2 +8b -3680 = 0 . . . . . . .put in standard form

  (b +4)^2 -3696 = 0 . . . . . . . add 16-16 to complete the square

  b = -4 +√3696 ≈ 56.795 . . . solve for positive b

Bob's drove about 57 mph on the trip.

the answer is b. 60. each interior angle in 120, so the exterior angle must be 60 in order to add up to 180

step-by-step explanation: