Question

place x+y<6 in graph

Answer 1

for this answer you have to do draw the graph of x+y=0
x= - y
or
y= -x
and thus find the values

Answer 2

HEY mate here is your answer.

just equate and draw the line and as per the condition shade the region.

here in my image there the line is not satisfying the condition so you can ignore that.

hope it helps you