Let 4/x+9/y= 1.

Then x+y

=(x+y)*(4/x+9/y)

=4+9x/y+4y/x+9

≥ 13+2√[(9x/y)*(4y/x)]

= 13+2*6

=25

If and only if 9x/y=4y/x

That is, when 2y=3x, the equal sign holds.

Substitute 4/x+9/y= 1.

X= 10，y= 15。

When x = 10 and y = 15, the minimum value of x+y is 25.

∴ Fill in 10 in the first bracket and 15 in the second bracket.