MIPS assembly addition program
The comments are misleading:

#Read second integer
li  $v0, 5      # Read 1st integer
la  $t1, B      # $t0 = A


umm... are we reading second or 1st? Bottomline is, do not overcomment the code.
syscall 5 leaves a value in $v0. The contents of $t0 (or $t1) is irrelevant during the syscall. Set them up when you need them:

li $v0, 5
syscall
la $t0, A
move    $t0, $v0

You store data to memory just to load them back. This is very anti-assembly. Generally you want to use registers as much as possible, and avoid memory as much as possible:

li $v0, 5
syscall
move $t0, $v0
...
li $v0, 5
syscall
# At this moment you have first integer in $t0, and the second in $v0.
# Just add them together. No memory access is necessary.


Consult your documentation on which registers are guaranteed to survive a syscall (I suspect, all of them besides $v0).
Nothing to simplify reading and printing.