The area under the speed curve tells you how much distance the vehicle covers.
The distance for first 30 s corresponds to the area of a rectangle with height <em>k</em> m/s and length 30 s, or
(<em>k</em> m/s) (30 s) = 30<em>k</em> m
The distance for the last 20 s corresponds to the area of triangle with height <em>k</em> m/s and length 20 s, or
1/2 (<em>k</em> m/s) (20 s) = 10<em>k</em> m
If the total distance traveled was 1.7 km = 1700 m, then
30<em>k</em> + 10<em>k</em> = 1700
40<em>k</em> = 1700
<em>k</em> = 42.5
