The revenue for each is $360.
10 x 36 = $360
12 x 30 = $360
But the profits vary because:
36 x 3 = $108 <---- this is how much it costs to make 36 birdhouses.
30 x 3 = $90
360 - 108 = $256
360 - 90 = $270
Therefore, selling 30 birdhouses for $12 each weekend nets Adam a higher profit.