What is the solution to the linear system show above?

Explain how you do each step what term makes it inconsistent y=2x - 4 ?

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?

Prove that the value of the expression 7^8–7^7+7^6 is divisible by 43.