What equation represents the temperature

Measures of the angle of r, 31 s (x+4) t (3x+9)

Sanya noticed that the temperature was falling at a steady rate of 1.4 degrees every hour from the time that she first checked her outdoor thermometer. by 6 a. m., the temperature had fallen 21 degrees. which expression can you use to find how many hours earlier she had first checked the thermometer?

Afurniture store is having a weekend sale and is offering a 20% discount on patio chairs and tables the sales tax on furniture is 6.25%