In order to find the line equation, first consider that you can write the general equation of a line as follow:
y - yo = m(x - xo)
where m is the slope and (xo,yo) is any point on the line.
Calculate the slope m by using the following formula:
![m=(y_2-y_1)/(x_2-x_1)](https://img.qammunity.org/2023/formulas/mathematics/high-school/78uaqhwt0aws3qfwxigaftpihnmb1gzxtp.png)
where (x1,y1) and (x2,y2) are any points on the line.
In this case, you have:
(x1,y1) = (2,5)
(x2,y2) = (6,21)
Replace the previous values of the parameters into the formula for m:
![m=(21-5)/(6-2)=(16)/(4)=4](https://img.qammunity.org/2023/formulas/mathematics/college/mmy8coxvk18uz44ua771exxou2d8td611m.png)
Now, use (xo,yo) = (2,5) and the previous value of m into the general equation for a line, and then solve for y, as follow:
![\begin{gathered} y-5=4(x-2) \\ y-5=4x-8 \\ y=4x-8+5 \\ y=4x-3 \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/va05y4z0qtjd7g61bqxuoblyapy46b0osz.png)
The previous result is the required equation in slope-intercept form.