math
posted by don .
a number of teachers were to receive 6 pens each ,but needed 4 more pens for them to be equally divided.if each teacher received 9 pens, 25 more pens would be necessary.how many pens are there

The number of pens is (6T  4), where T is the number of teachers. But the number of pens is also (9T  25), so (6T  4) = (9T  25). So 3T = 21, which means T = 7, i.e. there are 7 teachers. That means there are 38 pens. Check it: If 7 teachers received 6 pens each then you'd need 42 pens, which means you're four short: correct. Also if each of 7 teachers were to receive 9 pens, you'd need 63 pens  but you've only got 38, which means you need another 25: again, correct. So I reckon there are indeed 38 pens.