\(=12\left(3+9+88\right)\\ =12.\left(12+88\right)\\ =12.100\\ =1200\)
12 x 3 + 9 x 12 + 12 x 88
= 12 x (3+9+88)
= 12 x 100
= 1200
\(12\times3+9\times12+12\times88\)
\(=12\times\left(3+9+88\right)\)
\(=12\times\left(12+88\right)\)
\(=12\times100\)
\(=1200\)