Hello, thank you for taking the time to post your question!
The underlying equation that you want to use here is the point-slope form of a linear equation:
y−y1=m(x−x1)
For this set of values, we have a slope m=7 and a point (x1,y1)=(1,2).
Plugging these values into the point-slope equation gives you: y−2=7(x−1)
Solving that algebraically to put it into the slope-intercept form (y=mx+b) yields:
y−2=7x−7
y=7x−7+2
y=7x−5
To convert this equation to the standard form (Ax+By=C), you need to rearrange the terms: y=7x−5 −7x+y=−5
Multiplying the entire equation by -1 to make the coefficient of x positive gives: 7x−y=5
Meaning that the standard from of the equation of the line for these parameters is 7x - y = 5.