When he closed 1/4 of the tabs, he closed 1/4*400 = <<400*1/4=100>>100 tabs.
The number of windows tabs that remained open is 400-100 = <<400-100=300>>300
After reading some news from different pages, he closed 2/5 of the remaining tabs, a total of 2/5*300 = <<2/5*300=120>>120 pages.
The number of tabs that remained open is 300-120 = <<300-120=180>>180
If he closed half of the remaining tabs after further analyzing some pages, he closed a total of 1/2*180 = <<180/2=90>>90 pages.
The total number of tabs that remained opened is 180-90 = <<180-90=90>>90
#### 90