Because the slope doesn't tell you any actual points on the line. It only tells you whether the line tilts up or down, and how steeply. But the line could be way up there or way down under, with the same slope. You can't actually DRAW it until you know some point on it, and the y-intercept gives you one.
Find the LCM(lowest common multiple) of 8, 24 and 6.
The LCM of 8, 24 and 6 is 24.
We now want to turn all the denominators into 24 so we are going multiply 7/8 by 3 and 1/6 by 4. We won't need to turn the denominator of 3/24 into 24 because it's already 24
Whatever you do to the denominator you have to do to the numerator, so you also have to multiply the numerator of 7/8 by 3 and the numerator of 1/6 by 4
That now results in 21/8 + 2 3/24 + 6 4/24
Now you have to add all the fractions together which is going to equal to 28/24
Because 28/24 is more than the whole, subtract 28 from 24 which gives us 4. That 4 is now our new numerator
We are now going to all the whole numbers 6+2+1=9. Incase you're wondering, the '1' came from the 28/24
The answer you should get should be 9 4/24 or if it should be simplified it would be 9 1/6