Question

how can i solve |y|+3=3 ?

Answer 1

subtract 3 from both sides of '=' sign

Answer 2

first break the question into two cases: (i) y>=0 (ii) y<0

Answer 3

in this case y = 0 anytime

Answer 4

in general case where you have an absolute function on a variable
solve two equations (i) y>=0 then just remove the absolute (ii) y<0 then remove absolute and replace y with -y