Answer:
Daniel can buy 1 shirt
Explanation:
We can write an equation out of what they give us in the question.
Each shirt is $20, this can be represented as 20s.
All shipping on orders cost $10.99, this can be represented as 10.99s.
S represents how many shirts Daniel will buy.
The equation is written out like this:

Combine like terms:

Now solve

Therefore, if Daniel can only buy one shirt if he has only $50 to spend.
We can't have 2 shirts because that would exceed the $50 limit.
Hope this helps!!
- Kay :)