Question

a={(x,y):x,y are integers, x and y are less than equal to 0 and 4x +5y is less than equal to 40}and b={(x,y):x,y are integers,x and y are less than equal to 0 and 5x+4y is less than equal to 40} then A intersection B is

Answer 1

so ,
 x ≤ 0
 y ≤ 0

for    A = { (x,y) : 4x + 5y ≤ 40 } 
        B = { (x,y) : 5x + 4y ≤ 40 } 

so ploting the graph for the lines we find the common region as x ≤ 0 and y ≤ 0 

so A∩B = {(x,y) : x,y ≤ 0}