Yes, it's y= 1/2x because it's 1/2 miles (y) per x weeks
90+30x+30y. This is because the first day, 90 labels were printed, then you will use 30 times x to find how many minutes. This is the same for 30 times y. Youre trying to figure out how many minutes each machine printed for.
Since 20 is a factor of 40, the least common denominator of 3/20 and 9/40 is 40.
direct proportion y=kx , k is constant and k does not equal to 0.
17.5=k(21)
k=5/6
when x =39
y=5/6 ×39
y=32.5
