Evaluate each expression when s = 9 and t = 12.

2s – t

2(9) - 12

18 - 12

6

To evaluate the expression 2s - t when s = 9 and t = 12, we substitute the given values into the expression.

2(9) - 12 = 18 - 12 = 6

Therefore, 2s - t equals 6 when s = 9 and t = 12.