rate time(seconds) distance(how many steps) UP 2 d/2 d DOWN 3 d/3 d TOTAL 90
Let time taken to run up the stairs be T
Then time it takes him to run down = 90 - T
The distance equation is thus formed:
2T = 270 - 3T
2T + 3T = 270
5T = 270
T, or time taken to run up the stairs =, or