A3b to 30 km. if a , he is of b by 3/2 .of .

Initial speed:

Step-by-step explanation:

Both equations are concerned about the time differences between A and B. To avoid unknowns in the denominators,

First equation:

"A takes 3 hours more than B to walk 30 km."

.

.

When A doubles his pace, he takes only 1/2 the initial time to cover the same distance. In other words, now it takes only hours for A to walk 30 km.

Second equation:

"[A] is ahead of B by 3/2 hours [on their 30-km walk.]"

.

.

Hence the two-by-two linear system:

.

Solve this system for and :

Subtract the second equation from the first:

.

.

.

It initially takes 9 hours for A to walk 30 kilometers. The initial speed of A will thus be:

.

It takes 6 hours for B to walk 30 kilometers. The speed of B will thus be:

.

the answer is c.

step-by-step explanation: