On a certain trip, a motorist drove 6 miles at 20mph, 6 miles at 30mph, and 6 miles at 40mph. what portion of the total driving time did she spend driving 30mph?

  4/13

Step-by-step explanation:

Driving time is ...

  time = distance/speed

Then the ratio of times is ...

  6/20 : 6/30 : 6/40

  = 3/10 : 1/5 : 3/20

If we multiply by 20, we can get integer ratios:

  = 6 : 4 : 3

The middle ratio number represents the time spent at 30 mph, and the total of all ratio numbers represents the total driving time. Then the fraction spent at 30 mph is ...

  4/(6+4+3) = 4/13

Total driving time was 13/20 hours, or 39 minutes. Of that time, 12 minutes was spent driving at 30 mph.

answer: $201

step-by-step explanation: to get the answer, you first get 3 nieces that he sold and multiply it by 67 and get $201, so he earned $201 selling his nieces.

step-by-step explanation:

let

we know that

the y-intercept is the y-coordinate of the point when the value of x is equal to zero

so

the y-coordinate of the point a is the y-intercept

the answer part a) is

the value of y-intercept is

part b) find the slope m

we know that

the value of the slope is equal to

substitute the values

therefore

the answer part b) is

the value of the slope is equal to

the general answer is

the slope is

the value of y-intercept is