Arithmetic sequences have a common difference between consecutive terms.
Geometric sequences have a common ratio between consecutive terms.
Let's compute the differences and ratios between consecutive terms:
Differences:

Ratios:

So, as you can see, the differences between consecutive terms are constant, whereas ratios vary.
So, this is an arithmetic sequence.
Answer:
2
Step-by-step explanation:
Answer: Each shirt costs $1.25, and each hat costs $2.5.
Step-by-step explanation:
Let x= Cost per T-shirt, y = Cost per Hat.
As per given,
3x+3y=11.25 (i)
4x+2y=10 (ii)
Multiply 4 to equation (i)
12x+12y=45 (iii)
12x+6y= 30 (iv)
Eliminate (iv) from (iii), we get
6y= 15
⇒ y = 2.5
Put value of y in (i)
3x+3(2.5)=11.25
⇒3x+7.5=11.25
⇒3x= 3.75
⇒x= 1.25
Hence, each shirt costs $1.25, and each hat costs $2.5.
504÷1800=0.28
28% of her income goes to her rent