a: \(=24\left(25+37+38\right)=2400\)
\(3.25.8+4.37.6+2.38.12\\ =\left(3.8\right).25.\left(4.6\right).37.\left(2.12\right).38\\ =24.25.24.37.24.38\\ =24.\left(25+37+38\right)\\ =24.100\\ =2400\)
3.25.8+4.37.6+2.38.12
= 600 + 888 + 912
= 600 + ( 888 + 912 )
= 600 + 1800
= 2400.
136.48+16.272+68.20.2
= 1088 + 4352 + 2720
= 5440 + 2720
= 8160.