Question 1173839
<br>
Let the speed for the first part be x; then the speed for the second part is x+4.<br>
The time for each part is the distance, divided by the speed; the total time is 2 hours:<br>
{{{13/x + 17/(x+4) = 2}}}<br>
That equation is solved relatively easily with basic algebra.<br>
However, if you take a moment to look at the numbers in the equation, you might be able to see almost immediately that x=13 works....<br>
ANSWER: 13mph for the first 13 miles.<br>
CHECK: 13/13 + 17/(13+4) = 1+1 = 2<br>