<p>What are the questions that are like There are 200 kids in physics and 180 kids in Biology. there are 400 kids in that grade. How many kids are in both? Its not a very good example, but I know ive seen this kind, but i cant recall an actual exapmle off thee top of my head</p>
<p>Use this formula.
Works like a charm every time.
Total = A + B -both + neither</p>
<p>How about this example.
There are 100 seniors. 80 seniors play the flute and 50 seniors have cars and 10 senior do not play the flute nor have a car. How many seniors play a flute and have cars?
100 = 80 + 50 - both + 10
both = 40</p>
<p>Thanks, that helps a lot</p>