=391,23-3,0015+103,92

=492,1485

6,9 x 135 - 6,9 x 65 + 6,9 x 30

= 6,9 x ( 135 - 65 + 30 )

= 6,9 x 100

= 690

/HT\

567 x 23 + 433 x 23 = 23 x (567 + 433)

                                 =23 x 1000 = 23 000

TL:

\(\text{567 x 23 + 433 x 23}\)

\(=\left(567+433\right) x 23\)

\(=1000x 23\)

\(=23000\)

HT

\(\text{a) 7,25 x 0,34 + 2,75 x 0,34}\\ =0,34.\left(7,25+2,75\right)\\ =0,34.10\\ =3,4\)

\(\text{b) 10,79 x 0,24 – 0,24 x 0,79 }\\ =0,24.\left(10,79-0,79\right)\\ =0,24.10\\ =2,4\)

8,3 x 6,9 +8,3+3,1 x 6,9+3,1

= 8,3 x (6,9+1)  + 3,1 x (6,9 + 1)

= 8,3 x 7,9 + 3,1 x 7,9

= 7,9 x (8,3 + 3,1)

= 7,9 x 11,4

= 90,06

\(a.1,25\times5\times6,3\div0,125\times2\\ =\left(5\times2\right)\times\left(1,25\div0,125\right)\times6,3\\ =10\times10\times6,3=630\)

\(b.12,5\times6,9+0,1\times6,9\times865\times6,9\\ =6,9\times\left(12,5+86,5+1\right)\\ =6,9\times100=690\)

\(a,34,9+62,17-43,3+15,1-12,17-56,7\\ =\left(34,9+15,1\right)+\left(62,17-12,17\right)-\left(43,3+56,7\right)\\ =50+50-100\\ =100-100\\ =0\\ b,1,25\times2,5\times80\times40\\ =\left(1,25\times80\right)\times\left(2,5\times40\right)\\ =100\times100\\ =10000\)