Time spent babysitting by Lucy = Tl = 4 hours
Time spent babysitting by Maria = Tm = x * 4 hours
Now we need to determine for what values of x is Tm > Tl
⇒ x * 4 > 4
⇒ x > 1
So for x > 1, Mary spends more time babysitting than Lucy does
"find the percentile" means: "what percentage of the data points is below a certain value".
Here it's 138 data points out of 200, which is:

.
The answer is 69, and we phrase it as "the 69th percentile of data is at the value of 89.2"
You actually don't need to know the range to solve this!
Https://www.mathpapa.com/algebra-calculator.html
this website is very useful for answering questions like these
it walks you through it step by step
Let d represent the distance of the destination from the starting point.
After 45 min, Henry has already driven d-68 miles. After 71 min., he has already driven d-51.5 miles.
So we have 2 points on a straight line:
(45,d-68) and (71,d-51.5). Let's find the slope of the line thru these 2 points:
d-51.5 - (d-68) 16.5 miles
slope of line = m = ----------------------- = ------------------
71 - 45 26 min
Thus, the slope, m, is m = 0.635 miles/min
The distance to his destination would be d - (0.635 miles/min)(79 min), or
d - 50.135 miles. We don't know how far his destination is from his starting point, so represent that by "d."
After 45 minutes: Henry has d - 68 miles to go;
After 71 minutes, he has d - 51.5 miles to go; and
After 79 minutes, he has d - x miles to go. We need to find x.
Actually, much of this is unnecessary. Assuming that Henry's speed is 0.635 miles/ min, and knowing that there are 8 minutes between 71 and 79 minutes, we can figure that the distance traveled during those 8 minutes is
(0.635 miles/min)(8 min) = 5.08 miles. Subtracting thix from 51.5 miles, we conclude that after 79 minutes, Henry has (51.5-5.08), or 46.42, miles left before he reaches his destination.

To solve the given system of equations for substitution you:
1. Solve in one of the equations a variable.
For the given options the one that is correct is solve the first equation for y, by adding x to both sides: