SOLUTION: If Marta were able to increase her average cycling speed by 3.5 km/h, she would be able to cover in 2 h a distance at least as great as that which now takes 3 h. What is her best a

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Question 519582: If Marta were able to increase her average cycling speed by 3.5 km/h, she would be able to cover in 2 h a distance at least as great as that which now takes 3 h. What is her best average speed at present?
Answer by oberobic(2304) About Me  (Show Source):
You can put this solution on YOUR website!
s = speed
d = r*t is the distance equation
.
d = s*3 is the distance she travels in 3 hr now
.
d = (s+3.5)*2 is the distance she could travel in 2 hr if she went 3.5 km/hr faster
.
d = d
so
3s = (s+3.5)*2
3s = 2s +7
s = 7
.
s+3.5 = 10.5
.
Check the distances.
7*3 = 21
10.5*2 = 21
Correct.
.
Answer: Her best average speed at present is 7 km/h.