Answer:
I wrote answers to what I can see below. I'm happy to walk you through the rest of the problem if you can write out the rest in a comment, or LMK if you post a new pic/question.
Explanation:
Step 1 answers:
What do you want to know: How many bicycles, how many unicyles?
What do you know?
A bicycle has 1 seat and 2 wheels
a unicycle has 1 seat and 1 wheel
there are a total of 18 seats and 28 wheels
Step 2 answers:
let b = number of bicycles
let u = number of unicycles