Question

Values of f(x, y) are in the table:

x
1.0 1.1 1.2
0.0 6 8 10
0.2 5 7 9
0.4 4 6 5
y

Let Rectangle be 1<=x<=1.2, 0<=y<=.4
with Change in x = .1, change in y .2

Find the upper and Lower sum