One of the teachers at a school is chosen at random. The probability that this teacher is female is 3/5. There are 36 male teachers at the school. Work out the total number of teachers at the school.

So we know that 3/5 teachers in the school are female, and we also know that 36 teachers are male. 

The first thing to note is that if 3/5 are female, that leaves 2/5 to be male. This is because all of the possible probabilities need to equate to 1 (or in this case 5/5) altogether! 

Let's call the number of teachers "x" for now. We know that 2/5 of X is 36. 

To find X, it would be helpful to find what 1/5 would be, since we can then easily multiply this by 5 to find our whole value! 

To do this, we need to divide our 36 (2/5) by 2, which gives us 1/5 = 18. 

Therefore, to find the total number of teachers, all we need to do is multiply 18 by 5, which gives us 90 teachers!