Let "the number" = x
3x - 6 = 45 is your equation
Solve for x. Note the equal sign, what you do to one side, you do to the other. Do the opposite of PEMDAS.
Isolate the x. First, add 6 to both sides
3x - 6 (+6) = 45 (+6)
3x = 51
Isolate the x. Divide 3 from both sides
3x/3 = 51/3
x = 51/3
x = 17
17 is your answer for "a number".
hope this helps
