Hi!
1.)
a:A u B=

(The same elements are written once.)
b:A u C

c:B u C

Note:I used dots to mean commas .
Good work!
Answer:
x < 2.5
Step-by-step explanation:
Allen has already run 3 hours and will run x amount more to finish. This is 3+x. He must finish under or less than 5.5 hours. So 3 + x < 5.5. You solve and find x < 2.5.
35 x 0.14 = 4.9
The total tip would be $4.9