1.a. 86+357+14 = (86+14)+357 = 100+357 = 457
b. 72+69+128 = (72+128) +69 = 200+69 = 269
c. 25.5.4.27.2 = (25.4).(5.2).27=100.10.27=1000.27=27000
d. 28.64+28.36=28.(64+36)=28.100=2800
2. a. 135+360+65+40= (135+65)+(360+40)=200+400=600
b. 463+318+137+22 = (463+137)+(318+22)=600+340=940
c. = (20+30)+(21+29)+...+(24+26)+25
= 50+50+50+50+25
= 225