if statement with isblank

[jman9635]

user inputted value = v

if (isblank( v userinput cell),"", ???)

Looking for help with a formula that does the following to replace ??? that does the following

if(77<v,100,formula2)

if(77<v>4, formula2,)

if(v<4,0,formula2)

*formula2 is a vlookup that I have already 

[#2]

What’s the role of 77 in your formula? In the second line, 77 is always > 4. I suggest you specify your actual formula to elucidate the logic thereof to those who may be able to recommend a better alternative.