`a) (637×527-189)/(526×637+448)`
`= (637.(526+1)-189)/(526.637+448)`
`= [637.526+(637-189)]/(526.637+448)`
`= (637.526+448)/(526.637+448)`
`= 1`
`b) (64×50+44×100) / (27×38+146×19)`
`=64×50+44×100`
`=64×50+44×2×50`
`=64×50+88×50`
`=(64+88)×50`
`=152×50`
`=7600`
`27×38+146×19`
`=27×2×19+146×19`
`=54×19+146×19`
`=(54+146)×19`
`=200×19`
`=3800`
`=> 7800:3800= 2`