Answer:
7/20
Step-by-step explanation:
first of all you have to put the two fractions on the same denominators
1/4 (multiply by 5) and you will get 5/20
2/5(multiply by 4) and you will get 8/20
we have to add 5/20 and 8/20 that gives us 13/20
13/20 is the amount he drank
20/20 - 13/20 =7/20
7/20 is the amount of water left that Charlie has left

Distribute 3 throught the parentheses

Move the variable to the left-hand side and change its sign

Move the constant to the right-hand side and change its sign

Collect like terms

Divide both sides of the equation by -3

Since you have y alone on one side of the equation......
Use substitution and plug in 1/2x-4 for y in the other equation.

Distribute

Combine like terms

Add 8 to both sides

Divide by 4
and 
Plug this value in for x

Simplify

Multiply everything by 8 and simplify

Divide.....

Your answers are:

Answer:
the answer is 2
Step-by-step explanation:
So there is a real and imaginary axis
the midopint is just the average of them
average between the reals is (5-3)/2=2/2=1
average between imaginaries is (18i+2i)/2=20i/2=10i
center is 1+10i