Question

the graph represents a system of linear equations comparing the outside and inside temperatures y, in degrees fahrenheit, recorded at a school one day x hours after 8:00 a.m. after how many hours were the inside and outside temperatures equal? 6 hours 7 hours 8 hours 10 hours

Explanation:

Step1: Define equations for temps

Inside temp: $y_{inside} = 70$
Outside temp: Slope $m=\frac{70-58}{10-0}=1.2$, so $y_{outside}=1.2x+58$

Step2: Set temps equal, solve for x

$$70 = 1.2x + 58$$
$$1.2x = 70 - 58$$
$$1.2x = 12$$
$$x = \frac{12}{1.2} = 10$$

Answer:

10 hours