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

225/100 of last years cost. write each fraction as a decimal and as a percent

International calls require the use of a country code. many country codes a 3-digit numbers. country codes do not begin with a 0 or 1. there are no restrictions on the second and third digits. how many different 3-digit country codes are possible?

The price of an item has been reduced by 30%. the original price was $30. what is the price of the item now ?