Write the following number trick as an expression in two ways, one with parentheses and one without. For example, $4(x + 3)$ can also be written $4x + 12$.

1. Pick a number.

2. Multiply by $7$.

3. Subtract $15$.

4. Multiply by $2$.

   Hint:

   When writing the expression the first time, use parentheses to make sure the operations are carried out in the order written.
   Then, simplify the expression by removing the parentheses to write an equivalent expression.

   Answer:

   $2(7x − 15) = 14x − 30$