What is the output of this code and why?

Question

What is the output of this code?
a = [2,6,9]
a<< 3

a[1]+ = a[0]
puts a[1]

Answer 1

The output is 8 because:

a = [2,6,9] #Declares an array
a<< 3 #Has nothing to do with the output but it appends to the array

a[1] += a[0] # Pretty much sets the new value of the second value in the array by taking this second value and adding it to the first value so a[1] + a[0]

puts[1] # just prints the new value