a: =200+100=300
b: =918-400=518
d: =(1754-74+20):17=100
c: =26x20-17x20=20x9=180
\(a.257+149-57-49=257-57+149-49=200+100=300.\)
\(b.918-142-258=918-400=518.\)
\(c.26\cdot7-17\cdot9+13\cdot26-17\cdot11\)
\(=182-153+338-187=180.\)
\(d.1754:17-74:17+20:17\)
\(=\left(1754-74+20\right):17=1700:17=100.\)
a) ( 257 - 57 ) + ( 149 - 49 ) = 200 + 100 = 300
b) 918 - ( 142 + 258 ) = 918 - 400 = 518
c) 26. ( 7 + 13 ) - 17. ( 9 + 11 ) = 26. 20 - 17. 20 = 20. ( 26 - 17 )
= 20. 9 = 180
d) ( 1754 - 74 + 20 ) : 17 = 1700 : 17 = 100
