how could you estimate your altitude by finding the boiling point of water at your location

Question

its on page 209 number 40

Answer 1

boil temper av water dekreez bekauz av loer atmospeer pressure. . . . At see level, water boil at 212 deg Farenhite. . . . Engineers make a strate line approx av temper vs altitude . . . At 30,000 ft altitude, boil temper=160 deg F . . . delta temper=52 deg