`( x + 9 ) + ( x - 8 ) + ( x + 7 ) + ( x - 6 ) + ( x + 5 ) + ( x - 4 ) = 63,6 `
` x + 9 + x - 8 + x + 7 + x - 6 + x + 5 + x - 4 = 63,6 `
` (x + x + x + x+ x + x)+( 9 - 8 + 7 - 6 + 5 - 4) = 63,6 `
` 6x+3 = 63,6 `
` 6x= 63,6-3 `
` 6x= 60,6 `
`x=60,6:6`
`x=10,1`