What is the equation of the lined graph below

Kelly is three years younger than her sister. the sum of their ages is 34 years. how old is kelly and how old is her sister?

Brady has a 20 year fixed rate mortgage for $215,500 with monthly payments of 1,305.89.the annual interest rate is 4%. what is the total cost of the principal and interest for this loan rounded to the nearest dollar

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?