11+10=25+257+714-720+2040-20

11+10 = 21
25+25= 50
7+7= 14
14-7 = 7
20+20 = 40
40-20 = 20

11+10=21
25+25=50
7+7=14
14-7=7
20+20=40
40-20=20

Logikanya, (50+14+7) – (40+20) = 21
Itulah kenapa, 11+10 sama dengan angka-angka tersebut