3,4 with the slope of -2

Two equations that have the same solution are called equivalent equations e.g. 5 +3 = 2 + 6. An inverse operation are two operations that undo each other e.g. addition and subtraction or multiplication and division. You can perform the same inverse operation on each side of an equivalent equation without changing the equality.

Examples:

the reflexive property of equality tells us that any quantity is equal to itself a=a

the transitive property of equality tells us that if a quantity a equals quantity b, and b equals the quantity, c, then a and c are equal as well.

Since we know that 30 + 30 = 20 + 40 and that 30 + 30 = 60 we can substitute 30 + 30 for 20 + 40 and get 60 = 20 + 40. This is called the substitution property of equality.