Fill in the gap
25 36 _ 64 81 _

First change each value into improper fractions, which is 31/2 and 29/8. To divide fractions, keep the first one the same, change to multiplication, and flip the 29/8. So, the equation is now 31/2 * 8/29. Cross cancel the 2 & 8, making the equation 31/1 * 4/29. Multiply 31 by 4 to get the numerator, 124. Then divide 124 by 29 to get the final answer, ~4.27... So, she will need 5 buckets.