2. A student on the track team runs 45 minutes each day as a part of her training. She

begins her workout by running at a constant rate of 8 miles per hour for a minutes,

then slows to a constant rate of 7.5 miles per hour for b minutes.

Which equation describes the relationship between the distance she runs in miles, D,

and her running speed, in miles per hour?

A, a + b = 45

B. 8a + 7.5b = D

C. 0.865) + 7.506) = D

D. 8 (45 - b) + 7.5b = D

Algebra 1

D

Step-by-step explanation:

The basic equation to solve this would be D = RT, which is

D is Distance

R is Rate (speed)

T is time

To find total distance D, we can find individual distances for two legs of the whole.

First Leg:

R = 8

T = a

D = 8a

Second Leg:

R = 7.5

T = b

D = 7.5b

Total distance D is:

D = 8a + 7.5b

Moreover, we know student runs 45 minutes in total hence a + b = 45 or we can say a = 45 - b, so we can replace this in the equation found:

D = 8a + 7.5b

D = 8 (45 - b) + 7.5b

Answer choice D is right.