The number of solutions of the equation 2x+y=40 where both x and y are positive integers and x $\leq$ y is:

13 solutions.

For x = y, there are no integer solutions as there is no positive integer x for which 3x = 40.

For x < y, we have 13 integer solutions for each x from 1 to 13 as

(x, y) = (1,38), (2,36), (3,34)...... (13,14)

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