#1 is incorrect. The first equation says that his grandmother is not more than 80 years old. If you confine yourself to whole numbers, then she could be 80 but not more. That inequality should be written as g < 81 or if you are a purist, g≤ 80.
The second equation is correct. At the very most her age is equal to 3k - 3 so at most it would be written as g = 3k - 3.
Since it is not that much, you would write it as g ≤ 3k - 3
Answer:

Step-by-step explanation:
CP - the cost of painting the house for Painting USA company [$]
cP = 75 + 25 * 25 = 75 + 625 = 700 [$]
cU - the cost of painting the house for Upscale Home Painting company [$]
cU = 0 + 40 * 25 = 1000 [$]
cP < cU
The most cost effective is Painting USA company.
n - number of houres required to paint the house if the same cost for both companies
75 + 25 * n = 40 * n
40 n - 25n = 75
15n = 75 /:15
n = 5
The cost of paining the house is the same for both companies if the number of houres required to paint the house is 5.
They could have assembled total 336 different possible crews.
<em><u>Explanation</u></em>
Total number of trained pilots is 9 and geologists is 4.
The crew should be consisted of 2 pilots and 1 geologist. That means, <u>2 pilots are chosen from total 9 and 1 geologist is chosen from total 4</u>.
Number of ways for choosing 2 pilots from 9
and
Number of ways for choosing 1 geologist from 4 
So, the total possible number of different crews they could have assembled 
Answer:
The answer is below
Step-by-step explanation:
We are asked to find the perimeter of triangle CDE. The perimeter of a shape is simply the sum of all its sides, hence:
Perimeter of tiangle CDE = |CD| + |DE| + |CE|
Given that C(4, -1), D(4, -5), E(2, -3).
The distance between two points
is given as:

Therefore the lengths of the triangle are:

Perimeter of CDE = 4 + 2.83 + 2.83 = 9.66 units