Mr. Jones lives in City A and drives at a constant speed to City B, which is 400 km 2 of the distance at that same away. On the way back to City A, Mr. Jones drives 5 constant speed. Then, because of rain, he decreases his speed by 20 km/h. The round trip takes 11 hours. How fast did Mr. Jones drive during the rainy part of his trip from City B to City A?​

He traveled at 72km/hr during the rain

Step-by-step explanation:

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Given

--- distance

--- total time

Let his speed from city A till the rain starts on his return trip be

Let his speed from city during the rain be

So:

Required

Calculate

From the question, we understand that; he drives the whole 400 km and 2/5 of 400 km at

The distance covered during this period is:

And the time during this period is:

So, the distance during the rain is:

And the time during the rain is:

So, we have:

--- distance covered before the rain

--- distance covered when raining

---- time spent before the rain

--- time spent in the rain

Speed is calculated as:

Make distance the subject

So:

Recall that:

Make the subject

The expression becomes:

Collect like terms

Solve for

89

step-by-step explanation: