Salt is used in the largest quantity in Lydia's recipe.
Explanation
Required spices are......
Salt = [tex]\frac{1}{2}[/tex] teaspoon , Oregano = [tex]\frac{1}{3}[/tex] teaspoon, Crushed thyme = [tex]\frac{1}{4}[/tex] teaspoon and Black peeper = [tex]\frac{1}{8}[/tex] teaspoon
For finding the largest quantity, first we need to make the denominators of each fraction as equal and then identify the largest numerator.
The denominators are 2, 3, 4 and 8 and their LCM(Least common multiple) will be 24. So.....
[tex]\frac{1}{2}= \frac{1*12}{2*12}=\frac{12}{24} \\ \\ \frac{1}{3}=\frac{1*8}{3*8}=\frac{8}{24}\\ \\ \frac{1}{4}=\frac{1*6}{4*6}=\frac{6}{24}\\ \\ \frac{1}{8}=\frac{1*3}{8*3}=\frac{3}{24}[/tex]
As the largest numerator is 12 here, so the value of [tex]\frac{1}{2}[/tex] is largest among all the fractions.
Thus, Salt is used in the largest quantity in Lydia's recipe.