Adequate; sufficient; competent; sound; not fallacious; valid; in a commercial sense, to be depended on for the discharge of obligations incurred; having pecuniary ability; of unimpaired credit. My reasons are both good and weighty. Shakespeare My meaning in saying he is a good man is ...
With "at" we are referring to the skill of doing calculations, and with "with" we are referring to the numbers themselves. As you can see, there is little difference between those two, which is why both prepositions work and have basically the same meaning in this case. I can see why...
In a sting operation the police know with some level of certainty that if drug dealers are put in the right circumstance that they will sell drugs, thus the police work to ensure those conditions so that the criminals will freely choose to sell drugs at a pre-appointed time and location wh...