First, let's define that 1 and 1/4 is equal to 5/4. This will make our calculations easier by using an improper fraction. Let's also define 7.98 as 798/100.
In order to multiply fractions, you multiply the numerators and the denominators.
[tex]\frac{798}{100} \times\frac{5}{4} =\frac{3990}{400} = \frac{339}{40} = 9.975[/tex]