i think i know what you're tryna say

for amount realized, you also have to subtract the old basis (your basis in the property you exchanged to get the new property) so

50,000+3,500-1,000-old basis=amount realized

you are correct that gain recognized is the lesser of amount realized or boot received. you do not net the 3,500 and the 1,000 together in this situation because they are not the same. if you instead received 3,500 cash then you would net it together and it would be 2,500 boot received