FRACTIONS

a)

$\text{total pizza ate}\ =\ \frac13\ \text{of a pizza}\ +\ \frac14\ \text{of a pizza} \\~\\ \text{total pizza ate}\ =\ (\frac13+\frac14)\ \text{of a pizza} \\~\\ \text{total pizza ate}\ =\ (\frac{1\times4}{3\times4}+\frac{1\times3}{4\times3})\ \text{of a pizza} \\~\\ \text{total pizza ate}\ =\ (\frac{4}{12}+\frac{3}{12})\ \text{of a pizza} \\~\\ \text{total pizza ate}\ =\ \frac{7}{12}\ \text{of a pizza}$

b)

Technicallyyyy there could be any number of slices in the pizza. But 12 would be a good number of slices. That way Khalid could eat 4 full slices and his sister could eat 3 full slices.