2,5:1 per 4-1 1 per 5×20%

[tex] \frac{2.5}{ \frac{1}{4} } - \frac{11}{5 \times 20\%} \\ = 2.5 \times 4 - \frac{11}{100\%} \\ = 10 - \frac{11}{ \frac{100}{100} } \\ = 10 - 11 \\ = - 1[/tex]