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.
EF=9 cm. Both triangles are the same.
Try writing out the inequality.
$21<-⅔(4x+4)$ and see where u can go from there
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c .
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d.
Answer:
Step-by-step explanation:
perimeter of a square = 4 x length (L)
8x - 10 + 8x - 10 = 4L
rearrange the expression
8x + 8x - 10 - 10 = 4L
16x - 20 = 4L
divide both sides for L to stand alone
(16x - 20)/ 4 = 4L/4
(16x - 20)/4 = L
