44
18 + 13 = 31
-13 + 44 = 31
31 Because, twice 31 is 62. And, 62 plus 13 is 75.
31
-13
18 + 13= 31
2x + 5 = 31 2x = 31 - 5 = 26 x = 13
3/13
(13+47+31+10+20+50+36+54+122+4)/60==(13+47+31+[10+20+50]+36+54+122+4)/60 =(13+47+31+80+[36+54]+122+4)/60=([13+47]+31+80+90+122+4)/60=(60+31+80+90+122+4)/60=(31+122+4+60+80+90)/60=(153+4+60+80+90)/60=(157+60+80+90)/60=(157+140+90)/60=(157+230)/60=387/606 min. 27 sec.
13+13+13+13+13+13+13+13+13+13 = 13 * 10 = 130.
91
The mathematical statement 31 plus 31 would have an answer of 62.