`a) 162+275+173+227+725+438`
`=(162+438)+(275+725)+(173+227)`
`=600+1000+400`
`=(600+400)+1000`
`=1000+1000=2000`
\(a) 162 + 275 + 173 + 227 + 725 + 438 = ( 162 + 438 ) + ( 275 + 725 ) + ( 173 + 227 ) = 600 + 1000 + 400\)
\(\text{= ( 600 + 400 ) + 1000 = 1000 + 1000 = 2000}\)
162+275+173+227+725+438
= (162+438)+(275+725)+(173+227)
= 600+1000+400
= 1000 + 1000
= 2000