So, you need to know that the slope stays where it is, and that the 6 is not part of the final answer, so get rid of it.
y=2x+b
Now, submit x in for x, and y in for y.
3=2(1)+b
3=2+b
1=b
Put this in for the equation missing the b,
y=2x+1
Now check it; if you put 1 in for x, does y=3?
Convert 5% to .05 multiply that by total and youll get the tax amount and add the to the total then for the tip you multiply .15 by the total and shabam theres your answer
Multiply total students by the percentage:
600 x 80% = 600 x 0.80 = 480
480 students want more field trips.