Answer: 9t
Multiply t by the first option
6 x t = 36
Multiply t by the second option
7 x t = 42
Multiply t by the third option
8 x t = 48
Multiply t by the forth option
9 x t = 54
Observing all of the options you can see that 9t is the only option with 54 as its answer. Making the answer D.