How do you know that a =6 is a solution to a+5=11?

a + 5 = 11

You need to isolate the variable by subtracting from both sides

a + 5 - 5 = 11 - 5a = 6

The Addition/Subtraction Property of Equality states that if you add or subtract the same number to both sides of an equation the two sides still remain equal

:))

x + 107

step-by-step explanation:

let's say that the number he had before the mistake was x. then, he will have 107 dollars more than this, so the answer is x + 107.