Question

Identify the rule of inference that is used to arrive at the conclusion from the statements "if x is healthy to eat, then x does not taste good" and "tofu is healthy to eat."

Answer 1

The answer is Tofu does not taste good

To do the inference, it will be easier if the statement is simplified.  
statement 1 
"if x is healthy to eat, then x does not taste good"
Simplified: If A then B

statement 2
"tofu is healthy to eat."
Simplified: Tofu is A

Conclusion:
Because tofu is healthy to eat, then tofu does not taste good
Tofu does not taste good