Example

Solving DT=R\frac{D}{T} = R for TT

Solve the rational equation DT=R\frac{D}{T} = R for the variable TT by applying the strategy for solving equations with rational expressions. This formula is the distance-rate-time relationship written in a form where the target variable TT appears in a denominator.

Step 1 — Identify restricted values. The variable TT appears in the denominator, so T0T \neq 0.

Step 2 — Clear the fractions. The LCD is TT. Multiply both sides of the equation by TT:

TDT=TRT \cdot \frac{D}{T} = T \cdot R

Step 3 — Simplify. On the left, the TT in the numerator and denominator cancel:

D=TRD = TR

Step 4 — Isolate TT. Divide both sides by RR:

DR=T\frac{D}{R} = T

The solution is T=DRT = \frac{D}{R}.

This example demonstrates that even a familiar formula like D=RTD = RT becomes a rational equation when rewritten as DT=R\frac{D}{T} = R, because the variable TT now appears in a denominator. The same clearing-fractions technique used for numerical rational equations — multiplying both sides by the LCD — is applied here to eliminate the denominator before isolating the target variable with a simple division.

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Updated 2026-04-21

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