*Lời giải :
`x - 2020/12 + x - 2020/20 + x - 2020/30 + x - 2020/42 + x - 2020/72 = 16/9`
`-> (x + x + x + x + x) + (-2020/12 - 2020/20 - 2020/30 - 2020/42 - 2020/72) = 16/9`
`-> 5x + = 16/9 - 2020/12 + 2020/20 + 2020/30 + 2020/42 + 2020/72`
`-> x = (16/9 - 2020/12 + 2020/20 + 2020/30 + 2020/42 + 2020/72)/5`