Write the other number or expression in terms of the given variable.
A 3 foot board is cut into two pieces. If one piece measures x write the expression for the length of the other piece. Ok now I know the first term is 2x correct? where do I go from here?
no, 2x is not correct
think in terms of actual numbers ...
suppose you had a 3 foot board and cut off 1 foot
left over = 3-1 = 2
suppose you had a 3 foot board and cut off x ft.
left over = 3-x