The total daily costs for N units of production are 5N+300 Rand.

Income form selling N units is 15N Rand.

Thus total Profit is:

P(N) = 15N - 5B - 300 = 10N - 300.

Break even is when P(N)=0, which occurs when N=30.

If N=40, the P(40) = 100 Rand.

If N=10, then P(10) = -200 Rand

RonL