What operation is keeping the variable from being alone in 3x + 5 = 20?
The plus five. I should subtract five from both sides first.
Evidence: selects an inverse operationGood. After subtracting five, what is the next step?
Then I have 3x = 15, so I divide both sides by three. x equals five.
Evidence: isolates the variableHow could you check that answer?
Put five back in: three times five plus five is twenty.
Evidence: verifies by substitution