Year $1$

Sales revenue: $400$

cost: $464$

Result: $-64$

Year $2$

Sales revenue: $800$

Cost: $704$

Result: $96$

The structure of costs in relation to sales has remained the same in both years.

Calculate the company's profit margin $\%,$ critical point and margin of safety for years $1$ and $2.$

And here is the answer:

Margin $\%40$

Critical point $560$

Margin $\%$ and critical point are the same in years I and II

Safety margin in year I $-160$

Safety margin in year II $24.$

How do they calculate this?