Đáp án: ×
Giải thích các bước giải:
`A = (a × 7 + a × 8 - a × 15) : (1 + 2 + 3 + ........ + 10)`
`A= a × (7 + 8 - 15) : (1 + 2 + 3 + ........ + 10)`
`A = a × (15 - 15) : (1 + 2 + 3 + ........ + 10)`
`A = a × 0 : (1 + 2 + 3 + ........ + 10)`
`A =0 : (1 + 2 + 3 + ........ + 10)`
`A=0.`
___________
`B = (18 - 9 × 2) × (2 + 4 + 6 + 8 + 10)`
`B= (18 - 18) × (2 + 4 + 6 + 8 + 10)`
`B= 0 × (2 + 4 + 6 + 8 + 10)`
`B= 0.`
___________
`x × 5 + 122 + 236 = 633`
`x × 5 + 358 = 633`
`x × 5 = 633 - 358`
`x × 5 = 275`
`x = 275 : 5`
`x = 55.`
____________
`(x : 12) × 7 + 8 = 36`
`(x : 12) × 7 = 36 - 8`
`(x : 12) × 7 = 28`
`x : 12 = 28 : 7`
`x : 12= 4`
`x = 4×12`
`x=48.`
