Answer:
hmm
Step-by-step explanation:
Answer:
D, 8/15
Step-by-step explanation:
1/3 + 1/5
= 1(5)/3(5) + 1(3)/5(3)
= 5/15 + 3/15
= 8/15
12.15 km /h
Step-by-step explanation:
Step 1 :
Given
Distance between Airy Town to Brightvale = 9 km
Speed of Ricky = x km/h
Step 2:
Speed taken by Sam = x + y km/h
Time taken by Sam = 40 min = 40/60 hrs = 2/3 hrs
so we have (x+y) 2/3 = 9
Step 3:
Speed taken by Timothy = x - y km / h
Time taken by Timothy = 50 min = 50/60 = 5/6 hrs
= > (x-y) 5/6 = 9
Step 4 :
Solving the 2 equations
(x+y) 2/3 = 9 and (x-y) 5/6 = 9 we have
(2/3)x + 2/3(y) = 9 = > 2x + 2 y = 27
5/6(x) - 5/6(y) = 9 = > 5 x - 5 y = 54
Multiplying the first equation by 5 and the second by 2 we have ,
10 x + 10 y = 135 and 10 x - 10y = 108
Adding both,
20 x = 243 => x = 12.15.
This gives speed of Ricky as 12.15 km /h
