The relationship "P varies with D and U and inversely with V" can be written mathematically as:
P = K * (D * U) / V
where K is the constant of proportionality.
This equation shows that P is directly proportional to the product of D and U, and inversely proportional to V. As V increases, P decreases, while as D or U increase, P also increases, assuming all other variables remain constant. The constant of proportionality K is determined by the specific situation and the units used for each variable.