Question

A motorist drives for m hours at 120km/hr and n hours at 18km/hr. Altogether Somina drives 78km in 5 hours. Find m and n.​

Answer 1

Answer:

(0.118, 4.882)

Step-by-step explanation:

If a motorist drives for m hours at 120km/hr, then the Distance of the motorist is expressed as;

​Distance = Speed * time

​da = 120m

If he drives n hours at 18km/hr;

db = 18 * n

db = 18n

Speed of the motorist altogether is expressed as;

Speed =78km/5hrs

Speed = 15.6km/hr

SInce the total distnce is 78km

120m + 18n = 78 ....1 ..... * 1

If total time is 5hrs

m + n = 5....2 ...*18

Solve simultaneously

120m + 18n = 78

18m + 18n = 90

Subtract

120m - 18m = 78-90

102m = -12

m = 0.118 hrs

m =

Since m + n = 5

n = 5 - m

= 5 - 12/102

n = 4.882

Hence (m,n) is (0.118, 4.882)