Question 754603
30 mins at 20 km/hr = 10 km
24 mins at 10 km/hr =  4 km
Total of 14 km.
Right angled triangle with 
one of the sides = 10km
and the other = 4km
The answer is the hypotenuse
So, 10^2 + 4^2 = hypotenuse^2
    100 + 16  = hypotenuse^2
       116    = hypotenuse^2
       hypotenuse = square root of 116
So, shortest distance from C tp A = 10.8 km
To nearest metre = 11 metres

Hope this helps
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