289 x 57 + 311 x 45 + 289 x 43 + 311 x 55
= 289 x ( 57 + 43 ) + 311 x ( 45 + 55 )
= 289 x 100 + 311 x 100
= ( 289 + 311 ) x 100
= 600 x 100
= 60000
\(289x57+311x45+289x43+311x55\)\(=289x\left(57+43\right)+311x\left(45+55\right)\)
\(=289x100+311x100=100x\left(289+311\right)\)\(=100x600=60000\)