Which expression is equivalent to 4 - (-7)?

Abbey purchased a house using a fixed rate mortgage. the annual interest rate is 4.2% compounded monthly for 20 years. the mortgage amount is $235,000. what is the monthly payment on the mortgage? this isn't a multiple choice question have to show my work

Ageologist had two rocks on a scale that weighed 4.6 kilograms together. rock a was 0.5 of the total weight. how much did rock a weigh?

Two airplanes start at the same place and travel in opposite directions, one at 395 miles per hour and the other at 422 miles per hour. how many hours will it take for the planes to be 2451 miles apart?