Answer this question:Bobby has an aquarium with twice as many fish as Sarah's has. Sarah has 5 more fish in her aquarium than Tony does. Tony has 3 times as many fish in his aquarium as Billy does. Billy has 10 fish. How many fish do all 4 people have put together?
Since Tony has 3 times as many fish as Billy's 10, that means Tony has 3 * 10 = 30 fish. Sarah has 5 more fish than Tony's 30, meaning she has 5 + 30 = 35 fish. Bobby has twice as many fish as Sarah does, meaning he has 35 * 2 = 70 fish. Therefore, altogether there are 10 + 30 + 35 + 70 = 145 fish.
The answer is 145.

Answer this question:Ivy drinks 2.5 liters of water each day. How many bottles of 2-liter water should Ivy buy for her 4 days consumption?
For 4 days, Ivy consumes 2.5 x 4 = 10 liters of water. So Ivy should buy 10 / 2 = 5 bottles of 2 - liter water.
The answer is 5.

Answer this question:Out of the 80 students who took the biology exam, only 2/5 of them managed to score 100%. If a score below 80% qualified as failing, and 50 percent of the remaining students who didn't score 100% managed to score over 80%, calculate the number of students who failed the exam.
The number of students who scored 100% is 2 / 5 * 80 = 32. Out of the 80 students, 80 - 32 = 48 did not score 100%. If 50% of the students who did not score 100% managed to score over 80%, then 50 / 100 * 48 = 24 students scored over 80%. The number of students who failed is 48 - 24 = 24.
The answer is 24.

Answer this question:Ethyl bought Lucy two new dolls for her doll collection. This increased the doll collection by 25%. After the addition of the two new dolls, how many dolls are in Lucy's collection?
Let's let "x" be the original number of dolls in Lucy's doll collection. Then, 2 dolls equals an increase of 25%, and this can be written as x * 0.25 = 2. Solving for x we get x = 2 / 0.25 = 8 dolls in Lucy's original collection. After the gift of two new dolls, Lucy's collection contains 8 + 2 = 10 dolls.
The answer is 10.