Let's V the speed of the girl in step
v the speed of the escalator in step
L the length between ground and floor.
V*60+v*60=L ==> V+v=L/60
V*90-v*90=L ==> V-v=L/90
2V=L(3+2)/180
==>V=5L/360
Time to climb (in step) with v=0 (escalator standing still)
V*t=L==> t=L/V=L/(L*5/360)=72
The girl will count 72 steps.
Answer:
15 is the answer
Step-by-step explanation:
20×4=80
80-65=15
Miss lees class collected 3 more ball because 21-18 is 3. if i collect 18 balls and my friend collects 21 balls and then we add 21+18 we get 39 and then we put 39 in 13 equal groups we have 3in each group that is why they collected 3.
21-18=3
add 21+18=39
put in equal groups
divide 39 with 3 get thirteen make equal group get 3 in each group
*21-18=3
*21+18=39
*39 divided with 3=13
* 3 in each group
*Answer 3
The Mongols struggled to govern such an enormous empire.
