Hi there!
In order to answer your question, you'll need to use the cross product method:
3/4 cup flour → 1 1/8 teaspoon salt
1 cup flour → X salt
To make it easier to calculate, you can transform the fractions into decimals:
0.75 cup flour → 1.125 teaspoon salt
1 cup flour → X salt
(1.125 × 1) ÷ 0.75 = X salt
1.125 ÷ 0.75 = X salt
1.5 = X salt
If you want your answer to be in a fraction since the whole problem is given in fractions :
1.5 = 1 + 0.5 = 1 + 1/2 = 1 1/2
Your answer is: To maintain the ratio, when 1 cup of flour is used, 1.5 teaspoons of salt are required. OR 1 1/2 teaspoons are required. OR 1 and a half teaspoons are required.
There you go! I really hope this helped, if there's anything just let me know! :)