I need help how to find the answer

Use the elimination method to solve the systems of equations.choose the correct ordered pair. 7x+4y=39

Onnie is considering doing some long term investing with money that she inherited. she would like to have $50,000 at the end of 30 years. approximately how much money would lonnie need to put into an account earning 6% interest compounded annually in order to meet her goal?

When steve woke up. his temperature was 102 degrees f. two hours later it was 3 degrees lower. what was his temperature then?