So he multiplied the whole numbers which got him 15, then he only cross multiplied the fractions, giving him 9/8. That is what he did wrong. So to actually solve it, we need to convert from mixed numbers to improper fractions. To do this, we multiply the bottom with the whole number, and add with the top. For example, 3 1/2 would be 2×3, which is 6, then add 1, which is 7. So the improper fraction for 3 1/2 is 7/2. Doing the same for 5 4/9 we get 49/9. So now we have
[tex] \frac{7}{2} \div \frac{49}{9} [/tex]
Now, since we are dividing, we keep the first fraction, change the division to multiplication, and flip the second fraction, so we get
[tex] \frac{7}{2} \times \frac{9}{49} [/tex]
Now just multiplying top and bottom we get
[tex] \frac{63}{98} [/tex]
Divide the top and bottom by 7 and finally we get
[tex] \frac{9}{14} [/tex]
