Evaluate ab for a = 2(3/4) and b = 4/5

$$2 = 2*\frac{4}{4} = \frac{8}{4}$$

$$2\frac{3}{4} = \frac{8}{4} + \frac{3}{4} = \frac{11}{4}$$

When we multiply a and b we have

$$2\frac{3}{4}*\frac{4}{5} = \frac{11}{4}*\frac{4}{5} = \frac{44}{20} = \frac{11}{5} = 2 \frac{1}{5}$$

You may want to have a look at this website;

http://www.mathsisfun.com/fractions.html

also look at 'multiplying fractions'