Answer:
The number is 7
Step-by-step explanation:
certain positive number: x
x is multipled by 4:
4x
result of this is subtracted from the original number:
so original number minus 4x,
x - 4x
the result is 21 less than 0, this means negative 21
x - 4x = 0 - 21 = -21
do algebra:
-3x = -21
multiply both sides by -1
3x = 21
divide both sides by 3
x=7
(certain positive number: x) is equal to 7
So the expression is:

You can combine like terms, which are terms that contain the same variables raised to the same power. That means you can combine the two

.

The other terms can't be combined.
Your final answer should be

.
Answer:
width=3
Step-by-step explanation:
area=length X width
length=4 X width
=>area=4 X width X width
=>area=(2 X width)^2
=>36=(2 X width)^2
=>6=2 X width
=>width=3
Hello there!
Your answer is 114 feet
Hope I helped!
Let me know if you need anything else!
~ Zoe
Length(width + 30)=15,000 square meters, so the equation is l(w+30)=15,000, either 15,000 or 1,500 i cannot tell which number you were meaning to say because of where your comma is placed.