Question 1174986
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Given that his speed on level ground is the average of his uphill and downhill speeds, let the three speeds be<br>
x+y downhill
x on level ground
x-y uphill<br>
2 hours uphill and 3 hours on level ground covered 115 km:
2(x-y)+3(x) = 115<br>
2 hours downhill and 3 hours on level ground covered 135 km:
2(x+y)+3(x) = 135<br>
Solve the pair of equations using basic algebra.<br>
2x-2y+3x = 115
5x-2y = 115<br>
2x+2y+3x = 135
5x+2y = 135<br>
Comparing the two equations (i.e., subtracting one from the other)....<br>
4x = 20
x = 5<br>
Plug x=5 into one of the equations to solve for y; then use your x and y values to find the three speeds.<br>