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."

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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.]"

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Hence the two-by-two linear system:

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Solve this system for and :

Subtract the second equation from the first:

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

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

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-4

step-by-step explanation:

(-4+8)=-(4-8)=-8+4=-4