How to add 509+12 and get the answer to it

So basically you can add it with column addition or just simply break it down

Think about it lets break down 12 i got 10 and 2
then you can add it more easily

you could do 5019+10=519
then add 2 to get 521

Or you could do this

509
  12 +

521

so basically toy add 9+2 to get 11
then you carry the 1
then you do 1+1=2
then the 5 is left

so finally you get left with 512

You always work from left to right

(7 1/2) / (3/4) = 
(15/2) / (3/4) =
15/2 * 4/3 =
60/6 = 10 pieces