\(134\times21+15\times134+134\times66-134\times2\\ =134\times\left(21+15+66-2\right)\\ =134\times100=13400\)
= 134 x 21 + 15 x 134 + 134 x 66 - 134 x 2
= 134 x ( 21 + 15 + 66 - 2 )
= 134 x 100
= 13400
\(134\times21+15\times134+134\times66-268\\ =134\times\left(21+15+66-2\right)\\ =134\times100\\ =13400\)