Trust = (Knowledge + Reliability + Intimacy) / Self-interest

Knowledge has to do with the words we speak. In a sentence, we might say, "I can trust what she says about intellectual property; she is very knowledgeable on the subject. "

Reliability has to do with actions. We might say, for example, "If he says he'll deliver the product tomorrow, I trust him, because he's dependable." 

Intimacy refers to the safety or security that we feel when entrusting someone with something. We might say, "I can trust her with that information; she's never violated my confidentiality before, and she would never embarrass me." 

Self-interest refers to the focus of the person in question: in particular, whether the person's focus is primarily on himself or herself, or on the other person. Increasing the value of the factors in the numerator increases the value of trust. Increasing the value of the denominator, that is, self-orientation, decreases the value of trust.