Question

Trang can run up a hill at 3 m/s and down the hill at 7 m/s. It takes her 60 seconds in total to

run up and then down the hill. What distance does she cover going from the bottom to the
top of the hill?

Please step by step explanation:)

Answer 1

d=126 (m)

Explanation:

Let say:

d the distance from the bottom to the top

t1 the time used for running up

t2 the time for running down

`\left\{\begin{array}{ccc}d&=&3*t_1\\d&=&7*t_2\\t_1+t_2&=&60\\\end{array}\right.\\\\\\\left\{\begin{array}{ccc}d&=&3*t_1\\t_2&=&(3)/(7) t_1\\t_1+(3)/(7) t_1&=&60\\\end{array}\right.\\\\\\\left\{\begin{array}{ccc}t_1&=&(60*7)/(10)=42 \\\\t_2&=&(3*42)/(7)=18\\\\d&=&3*42=126\\\end{array}\right.\\`