e) Akili, Njozi and Aziz ring their bells. Akili rings his after 2 minutes, Njozi after every 3 minutes and Aziz after 4 minutes. After how many minutes will all the bells ring together? f) The school

The bells ring every 2, 3, and 4 minutes. We need to find the LCM of 2, 3, and 4.

Multiples of 2: 2, 4, 6, 8, 10, 12, ...
Multiples of 3: 3, 6, 9, 12, ...
Multiples of 4: 4, 8, 12, ...
The smallest common multiple is 12.

Alternatively, using prime factorization:
$2 = 2^1$
$3 = 3^1$
$4 = 2^2$
LCM = $2^2 \times 3^1 = 4 \times 3 = 12$.

All the bells will ring together after $\boxed{12 \text{ minutes}}$.

If $\frac{3}{4}$ of the teachers are female, then the remaining fraction are male.
Fraction of male teachers = $1 - \frac{3}{4} = \frac{4}{4} - \frac{3}{4} = \frac{1}{4}$.

Total number of teachers = 80.
Number of male teachers = $\frac{1}{4} \times 80$.
Number of male teachers = $\frac{80}{4} = 20$.

There are $\boxed{20 \text{ male teachers}}$ in that school.