219-7x(x-1)=100
⇒ 7x(x-1)=219-100
⇒ 7x(x-1)=119
⇒ x-1=119:7
⇒ x-1=17
⇒ x=17+1
⇒ x=18
219-7(x+1)=100
7(x+1)=219-100
7(x+1)=119
x+1=119:7
x+1=17
x=17-1
x=16
`@` `\text {Ans}`
`\downarrow`
`219 - 7 \times (x - 1) = 100`
`=> 7 \times (x - 1) = 219 - 100`
`=> 7 \times (x - 1) = 119`
`=> x - 1 = 119 \div 7`
`=> x - 1 = 17`
`=> x = 17 + 1`
`=> x = 18`
Vậy, `x = 18.`
219 - 7 \(\times\)( \(x\) - 1) = 100
7 \(\times\) ( \(x\) - 1) = 219 - 100
7 \(\times\) ( \(x\) - 1) = 119
\(x\) - 1 = 119 : 7
\(x\) - 1 = 17
\(x\) = 18
