answer :
x = 0,y = 4
explanation :
just plug in the value of x and y from each set in the function and compare which one gives the greatest value.
for (0,0) : x + 4y = 0 + 4(0) = 0
for (6,0) : x + 4y = 6 + 4(0) = 6
for (5,2) : x + 4y = 5 + 4(2) = 13
for (0,4) : x + 4y = 0 + 4(4) = 16
from the above values, we can collect that at point (0,4), the value of objective function x +4y is maximum.