Quick approach: Write out 3x+4y=11 and then replace the constant (11) with C:
3x+4y=C. Next, substitute 8 for x and 0 for y, obtaining:
3(8) + 4(0) = C. Then C = 24, and the desired equation is 3x+4y=24.
You could, of course, solve 3x+4y=11 for y to obtain the slope of the original line, and then substitute 8 for x and 0 for y into the point-slope formula for a straight line, or the slope-intercept formula. The end result should be the same as above: 3x+4y=24