#### Explanation:

$S I = \frac{P \times R \times T}{100}$

Applying the formula for simple interest we get:

$S I = \frac{800 \times 2 \times 5}{100}$

$S I = \frac{8 \cancel{00} \times 2 \times 5}{1 \cancel{00}}$

$S I = 8 \times 2 \times 5$

$S I = 80$