a) 12 x 53 + 53 x 172 - 53 x 84
= 53 x ( 12 + 172 - 84 )
= 53 x 100
= 5300
b) 35 x 34 + 35 x 95 + 65 x 75 + 65 x 54
= ( 35 x 34 + 35 x 95 ) + ( 65 x 75 + 65 x 54 )
= 35 x ( 34 + 95 ) + 65 x ( 75 + 54 )
= 35 x 129 + 65 x 129
= ( 35 + 65 ) x 129
= 100 x 129
= 12900
c) 86 x 7676 - 8686 x 76
= 86 x 76 x 101 - 86 x 101 x 76
= 0
d) 6969 x 45 - 4545 x 59
= 69 x 101 x 45 - 45 x 101 x 59
= 45 x 101 x ( 69 - 59 )
= 4545 x 10
= 45450
e) 351 x 67 + 351 x 16 + 649 x 83
= 351 x ( 67 + 16 ) + 649 x 83
= 351 x 83 + 649 x 83
= ( 351 + 649 ) x 83
= 1000 x 83
= 83000
f) 42 x 53 + 47 x 156 - 47 x 114
= 42 x 53 + 47 x ( 156 - 114 )
= 42 x 53 + 47 x 42
= 42 x ( 53 + 47 )
= 42 x 100
= 4200
g) 3851 : 500 + 1149 : 500
= ( 3851 + 1149 ) : 500
= 5000 : 500
= 10
h) 4783 : 300 - 1783 : 300
= ( 4783 - 1783 ) : 300
= 3000 : 300
= 10
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