Answer:

or

Step-by-step explanation:
Hello!
Use the quadratic formula: 
First, let's convert our equation to standard form of a Quadratic: ax² + bx + c = 0
3x² = 80
3x² - 80 = 0
Note, thats the value of b will be 0, as there is no "bx"
Now, solve:
Plug in values
Simplify the radical (Discriminant)
Pull out perfect squares
Reduce factors
The solutions are 
21.3 is the correct answer.
Answer:
35$
Step-by-step explanation:
If one muffin is 5 dollars and you buy 7 then just multiple them and get 5x7=35
Yes. / = divide & * = multiply.
As for the equation, 10 divided by 1 2/3 is 15
Answer:
x = -5
Step-by-step explanation:
Multiply 3 by (6x - 4x) = 18x - 12x
18x - 12x = -30
6x = -30
x = -30 /6
x = -5