Make each known side into a ratio like so...
75/6
(Because 75 is the shadow casted by the building, and 6 is the shadow casted by sarah)
and 50/x
(50 is how tall the building is and sarah's height is what needs to be found)
Therefore,
75 50
---- -----
6 x
Do cross products;
50 x 6 = 75 x X
300 = 75x
Divide by 75
x = 4ft
If by standard from you mean numbers (123) and not words then
1 milllion=1000 thousand or 1000*1000 or 1,000,000
1 billion=1000 million=1000*1000*1000=1,000,000,000
so 7billion=7*1000*1000*1000=7,000,000,000
Given a point in coordinates form

, one can compute the cartesian form like this:

We have:

We get the cartesian form then:
Answer:
Their slopes are opposites