The difference between the highest and lowest temperature is 85°F.
X=area of Sahara.
y=area of the Gobi Desert.
We suggest this system equations:
x+y=4000000
x=7y
solve by susbstitution method.
(7y)+y=4,000,000
8y=4,000,000
y=4,000,000 / 8=500,000
x=7y
x=7(500,000)=3,500,000
The area of Sahara=3,500,00 miles².
The area of the Gobi Desert=500,000 miles²
To check:
Te sum of their areas is : 3,500,000 miles²+500,000 miles²=4,000,000 miles²
Te area of sahara (3,500,000 miles²) is 7 times the area of the Gobi Desert (7*500,000 miles²=3,500,000 miles²).
You first convert everything to minutes
3hrs= 60x3=180mins
1hr= 60x1=60mins
then you add 20 to 180
200
and you also add 48 to 60
104
200-104=
96
Then you convert to hrs and mins
96-60=36
1hr 36mins
Therefore, the equation of circle is: 
<h3><u>
What is a circle?</u></h3>
- All points in a plane that are at a specific distance from a specific point, the center, form a circle. In other words, it is the curve that a moving point in a plane draws to keep its distance from a specific point constant.
- The radius of a circle is the separation between any point on the circle and its center.
- The radius must typically be a positive integer. Except when otherwise specified, this article discusses circles in Euclidean geometry, namely the Euclidean plane.
- A circle, specifically, is a straightforward closed curve that separates the plane into its inner and exterior.
Here we know that
but we are not given the radius.
However, we can find the radius by using the distance formula.
, where
and 
Putting the values, we get:

The radius comes out to be:

An equation of the circle with center
and radius r is

Now, substituting the values, we get:

Therefore, the equation of circle is:

Know more about circles with the help of the given link:
brainly.com/question/10618691
#SPJ4
This is a geometric sequence with a common ratio of 2
an = a1 * r^(n - 1)
n = term to find = 21
a1 = first term = 0.05
r = common ratio = 2
now we sub
a21 = 0.05 * 2^(21 - 1)
a21 = 0.05 * 2^20
a21 = 0.05 * 1048576
a21 = 52428.80 <==== after working 21 days