Equation of a line in slope-intercept form:
[tex]\begin{gathered} y=mx+b \\ \\ m\colon\text{slope} \\ b\colon y-\text{intercept} \end{gathered}[/tex]
1. Find the slope: Use two ordered pairs (x,y) in the next formula:
[tex]\begin{gathered} m=\frac{y_2-y_1}{x_2-x_1} \\ \\ \text{Ordered pairs (3,56) and (7,85)} \\ m=\frac{85-56}{7-3}=\frac{29}{4}=7.25 \end{gathered}[/tex]
Slope: m=7.25
2. Find the y-interept: Use one ordered pair and the slope to find b:
[tex]\begin{gathered} \text{ordered pair: (3,56)} \\ x=3 \\ y=56 \\ \\ \text{Slope: m=7.25}_{} \\ \\ y=mx+b \\ 56=7.25(3)+b \\ 56=21.75+b \\ 56-21.75=b \\ \\ b=34.25 \\ \\ b\approx34 \end{gathered}[/tex]
y-intercept: b= 34
Then, the equation of the line is:
[tex]y=7.25x+34[/tex]
