a: =(135+365)+245+55=300+500=800
b: =136(24+72+1)=136*97=13192
c: =1999(56+55-1)=219890
\(a,=\left(135+365\right)+\left(245+55\right)=500+300=800\)
\(b,=136.\left(24+72+1\right)=136.97=13192\)
\(c,=1999.\left(56+55-1\right)=1999.100=199900\)
`a) 135 + 245 + 365 + 55`
`= (135+365)+(245+55)`
`= 500 + 300`
`= 800`
`b) 136 xx 24 + 72 xx 136 + 136`
`= 136 xx 24 + 72 xx 136 + 136 xx1`
`= 136 xx (24+72+1)`
`= 136 xx 97`
`= 13192`
`c) 1999 xx 56 + 1999 xx 55 - 1999`
`= 1999 xx 56 + 1999 xx 55 - 1999xx1`
`= 1999xx(56+55-1)`
`= 1999xx110`
`= 219890`