Question: A lemonade stand sold only small and large cups of lemonade on Tuesday. 3/5 of the cups sold were small and the rest were large. If the large cups were sold for 7/6 as much as the small cups, what fraction of Tuesday's total revenue was from the sale of large cups?

Explanation: Since the large cups were sold at 7/6 as much per cup as the small cups.

Comment: It is nowhere written that EACH large cup sold at 7/6 of the EACH small cup.
The question statement rather suggests that Total revenue from large cups was 7/6 of the total revenue from small cups.

is the answer 7/16?

You have been catching a lot of details, Anand. Thanks for close inspection.

However, I am not entirely convinced on this one.

Note that if you interpret the questions stem as you suggest, and T = grand total revenue, L = large cup total revenue, and S = small cup total revenue, then:

T = L + S
T = (7/6)S + S
T = (13/6)S
S = (6/13)T

Therefore L = (7/13)T, and we wouldn't need either statement to answer the question! That is not allowed to happen on the GMAT.

That said, I agree you have a point, and there is certainly no harm in adding "each" to the wording of the question. We will likely investigate the typical GMAT wording before deciding. Our equal and primary goals are always GMAT-likeness and correctness. Thanks again!