Let's assume that Ethan still needs to sell x hot dogs to reach his goal of selling more than $70 worth of hot dogs today.
The inequality to represent the number of hot dogs Ethan still needs to sell is:
3.5x + 28 > 70
Now, we can solve for x as follows:
3.5x + 28 > 70
3.5x > 70 - 28
3.5x > 42
x > 42/3.5
x > 12
Therefore, Ethan needs to sell more than 12 hot dogs to reach his goal of selling more than $70 worth of hot dogs today.
The solution set in terms of the whole number of hot dogs Ethan needs to sell is {13, 14, 15, ...}. Since we cannot sell a fractional part of a hot dog, we need to round up to the nearest whole number. Thus, Ethan needs to sell at least 13 hot dogs.