Question 775626
Suppose the boy travelled x miles on bicycle.
Therefore, he must have travelled (27 - x) miles on foot. (since total distance travelled is 27 miles)


Time (in hours) taken for riding bicycle = (Distance covered on bicycle)/(Speed of bicycle) = x/15


Time (in hours) taken for walking = (Distance covered on foot)/(Speed of walking) = (27 - x)/4.5


Total time taken: {{{x/15 + (27 - x)/4.5 = 2.5}}}

{{{3x + 10(27 - x) = 2.5*45}}}
{{{3x + 270 - 10x = 112.5}}}
{{{7x = 157.5}}}
{{{x = 22.5}}}

Hence, the boy travelled 22.5 miles on bicycle and remaining (27 - 22.5 =) 4.5 miles on foot.