`B=45a+79b+30a-54b`
`=75a+25b`
`=25(3a+b)`
`=25.2021`
`=50525`
\(B=45a+79b+30a-54b=75a+25b=25\left(3a+b\right)=25.2021=50525\)
\(B=45a+79b+30a-54b\)
\(B=\left(45a+30a\right)+\left(79b-54b\right)\)
\(B=75a+25b\)
\(B=25\left(3a+b\right)\)
\(B=25.2021\) (vì 3a+b=2021)
B=45a+79b+30a−54b=75a+25b=25(3a+b)=25.2021=50525
Ta có: \(45a+79b+30a-54b\)
\(=75a+25b\)
\(=25\cdot2021=50525\)