a.
(9/4)/(1/2)
b.
For one pound of tomatoes we would end up doubling the recipe.
The equation would look like this
2((9/4)/(1/2)
You would distribute and get
(18/4)/(2/2)
which when simplified once is
(9/2)/(1)
but once simplified even more you get your answer.
4.5 cups of lettuce for 1 cup of tomatoes