The answers for 13 and 14 are attached in the file.
2/2 part of the equation is ≤ B
maybe 30/100 ≤ B
20 cats * ( 1 bag of food / 5 cats per month ) = 4 bags of food per month to feed all 20 cats
To solve for this, set up a proportion.
21/40 = x/100.
Cross multiply the fraction's numerators with the denominators;
21 x 100, 40 and x.
2100/40x.
Divide both numbers by 40 to get x.
2100/40 = 52.5
21 is 52.5% of 40.
I hope this helps!