$\text{Đáp án :}$
`1.`
`A=128 × 68 + 16 × 256`
`= 128` x `68 + 16` x `128` x `2`
`= 128` x` ( 68 + 16 `x `2 )`
`= 128`x`100`
`= 12800`
`B= 95,72` × `3,57 + 3,57` × `4,28`
`= 3,57` x `( 95,72 + 4,28)`
`= 3,57` x `100`
`= 357`
`2.`
`a, 5×(4+6×x)=290`
`4+6×x = 290÷5`
`4+6×x=58`
`6×x = 29/2`
`x= 29/2÷6`
`x = 29/12`
`b, (15×24-x)÷0,25=100÷1/4`
` (15×24-x)÷0,25=400`
`15×24-x = 400÷0,25`
`360-x=100`
`x = 260`
`c,`7,2÷2,4×x=4,5
` 2,4 × x = 7,2 ÷ 4,5`
` 2,4 × x = 8/5`
`x = 8/5 ÷ 2,4`
`x = 2/3`
$\text{Good luck !}$