1. a.(23425+16585)+(11832+9068)=251010+20900=271910
b.(18870+41130)+(24590+10410)=60000+35000=95000
c.(14236+21264)+(30645+50255)+(12242+17758)=35500+80900+18982=135382
2. 87900-x=13600
x=87900-13600
x=74300
3. a.29600+14500=44100
986000-(44100+29600)=986000-14500=971500
b.986000-(29600+14500+29600)=971500