C and D.............................
<span>Step 1: 0.4 = 4⁄10</span>
<span>Step 2: Simplify 4⁄10 = 2⁄5</span>
50km to 80km is 30km
10c to -80c is -90c
and since it linear (Which means the change is constant or the same)
every 10 km show a -30c decrease
so
60 km is -20c
70km is -50c
answer is c
Answer:
Step-by-step explanation:
Let the speed of Masha = s, speed of Dasha = d
- Distance = 20 km
- Time difference = 20 min = 1/3 hr
- Speed difference = 2 km/h
<u>As per above info we get following equations:</u>
- s = d + 2
- 20/s + 1/3 = 20/d
<u>Substitute s and solve for d:</u>
<u>Get rid of fraction by multiplying all terms by 3d(d + 2):</u>
- 60d + d(d + 2) = 60(d + 2)
- 60d + d² + 2d = 60d + 120
- d² + 2d = 120
- d² + 2d + 1 = 121
- (d + 1)² = 11²
- d + 1 = 11
- d = 10
<u>Find s:</u>
<u>The answer is</u>
- Masha's speed 12 km/h and Dasha's speed 10 km/h
