We have a question: Martha receives a daily allowance of $12. She decides to save half of this amount every day. In the first week she kept her commitment with the exception of one day when she saved only a quarter of this amount. How much has she saved at the end of this week?
And an answer: 39
So how you got the answer?
Half of $12 is (1 / 2) * $12 = $6. There are 7 days in a week so if she saved half every day except one then she saved half for 7 - 1 = 6 days. She saved $6 for 6 days for a total of $36. A quarter of $12 is (1 / 4) * $12 = $3. She saved a quarter once for a total savings of $3 + $36 = $39.

We have a question: A psychologist believes one in every four people has a disorder he calls ZYX syndrome. The clinic where he works has recently doubled its previous number of 26 patients. How many patients is the psychologist likely to diagnose with ZYX syndrome?
And an answer: 13
So how you got the answer?
The clinic has 26 * 2 = 52 patients. The psychologist believes 1 / 4 of people have the disorder, so he is likely to diagnose 52 / 4 = 13 patients with ZYX syndrome.

We have a question: While Greg was camping with his family for a week, it rained for 3 days. When he looked at the weather records, he saw that the amount of rain was 3 mm, 6 mm, and 5 mm on the three days. During the same week, it rained 26 mm at his house. How much less rain did Greg experience while camping?
And an answer: 12
So how you got the answer?
While camping there was 3 + 6 + 5 = 14 mm of rain in 3 days. Greg experienced 26 – 14 = 12 mm less rain at the campsite.