V(4)=4²-3×4=16-12=4 is the result of substituting t=4 in the function.
we know the Inn is charging 155.82 and that's 100% plus 6%, namely 106% of an amout of say that is "x", being the 100%.
since we know that 155.82 is 106%, what is "x"?

What are you asking here i think it should be 20:100