Answer:
X. The letter "x" is often used in algebra to mean a value that is not yet known. It is called a "variable" or sometimes an "unknown". In x + 2 = 7, x is a variable, but we can work out its value if we try!
Step-by-step explanation:
The length of one side is 5
Answer:
-21
Step-by-step explanation:
3×(-7) = - 21
Three times minus seven equals minus twenty one.
Answer:

Step-by-step explanation:

Gives the above answer