in Excel, if I have a function, such as pV=nRT, (p, V, n, R, T are number), traditional, I can make boxes to input the value of p, V, n, R, then T=pV/nR. However, now I want to make it that I have 5 boxes for those value, as Excel know the relationship pV=nRT, if I type in any 4 value it will calculate the leftover box. How can I type it?