Please help explain y = 2x + 3

Math it's appreciated. (picture provided)

Find the values of the variables and the lengths of the sides of this kite.

Pamela has a 30-year, 5.75% mortgage on her $250,000 home. she has been paying on it for 5 years, and has recently hit some financial trouble. if her lender agreed to lower the interest rate on her $231,905.47 balance to 5.5%, what will her new payment be for the remainder of the loan?