` 1/1.4+1/4.7+1/7.10+...+1/97.100= (0,33.x)/2009`
` 3/1.4+3/4.7+3/7.10+...+3/97.100=0,99.x/2009
` 1 - 1/4 + 1/4 - 1/7 + ... + 1/97 - 1/100 = (0,99.x)/2009`
` 1 - 1/100 = ( 0,99.x)/2009`
` 99/100 = (0,99.x)/2009`
`x = (99.2009) : (100.0,99)`
`x = 198891 : 99`
`x = 2009`