Question

Use the properties of addition and multiplication
to find the missing number. (And what property is this)
5x = x·___

Answer 1

You can multiply any two numbers in any order

for example

2*3 = 6
3*2 = 6

or

7*9 = 63
9*7 = 63

Answer 2

this rule also applies to variables because variables are just placeholders for numbers

that means 5*x = x*5

this rule is formally called the commutative property of multiplication

http://www.aaamath.com/pro74bx2.htm