What is -2+(-4) I need help with it because id not understnad how to add integers

Ihave trouble finding the nth term of a linear sequence

Acomputer store bought a program at a cost of $10 and sold it for $13. find the percent markup

The probability that an adult possesses a credit card is .70. a researcher selects two adults at random. by assuming the independence, the probability that the first adult possesses a credit card and the second adult does not possess a credit card is: