Question

If a line crosses the y-axis at (0,1) and has a slope of 4/5, what is the equation of the line ?

Answer 1

The slope intercept form of a line is y=mx+b, where m is the slope and b is the y-intercept (the value of y when x=0).  We are given that the slope is 4/5 and the point (0,1) so we know m=4/5 and b=1 so:

y=4x/5+1  now to rearrange into standard form ax+by=c

y=(4x+5)/5

5y=4x+5

5y-4x=5

So the answer is D.

However, by convention, in standard form, the equation is usually expressed with a positive coefficient for x.

5y-4x=5 SHOULD be expresses so the x has a positive coefficient, divide both sides by -1 and you have the technically correct form:

4x-5y=-5

Apparently whomever/whatever posed this question to you was unaware of this convention :P