The total number of gifts = x+y.
The inequality is:

Key chains cost $1, Magnets $0.50
Total Cost = x + 0.5y
Inequality is:

Without graphing you can solve system by using substitution:

This is one solution where the maximum x value is given.
So the most keychains that can be purchased is 16. However, because magnets are cheaper, more can be purchased as long as cost remains under 20.
If you solve both inequalities for "y", you get the upper and lower bounds for how many magnets can be purchased given a quantity of keychains.

This is complete solution which gives all possible combinations.
(Graph is Attached)
Answer:
15.6 inches
Step-by-step explanation:
Here we want to find the length of the missing side
Mathematically, we can use Pythagoras’ theorem
The theorem states that the square of the hypotenuse equals the sum of the squares of the two other sides
Let the missing side be x
18 is the side that faces right angle and this is the hypotenuse
Thus, we have ;
x^2 + 9^2 = 18^2
x^2 = 324 - 81
x^2 = 243
x = √(243)
x = 15.6 in
Answer:

Step-by-step explanation:
We have the equation 
In order to solve for x, we need to get all of the x's to one side and everything else to the opposite side

First, we can add 1 to each side

Now, we can add x to each side

Next, we can divide each side by 2

And here is our answer.
4x-3+7x+1
Ones with a variable: 4 & 7
Only whole number: -3 & 1
The answer is option two: -3 and 1; 4x and 7x
The interior angles of a triangle add up to 180 degrees
a = 1st angle, b = 2nd angle, c = 3rd angle
c = 6a
b = a + 60
a + b + c = 180
a + (a + 60) + (6a) = 180
8a + 60 = 180
8a = 180 - 60
8a = 120
a = 120/8
a = 15 <=== here is one angle
b = a + 60
b = 15 + 60
b = 75 <=== and another one
c = 6a
c = 6(15)
c = 90 <=== and the last angle