Question: 12r=30
1. **State the problem:** Solve the equation $$12r=30$$ for the variable $$r$$.
2. **Formula and rules:** To isolate $$r$$, divide both sides of the equation by $$12$$. Remember, dividing both sides of an equation by the same nonzero number keeps the equation balanced.
3. **Intermediate work:**
$$\cancel{12}r=\frac{30}{12}$$
4. **Simplify the fraction:**
$$r=\frac{30}{12}=\frac{5}{2}$$
5. **Final answer:**
$$r=\frac{5}{2}$$ or $$r=2.5$$.
This means that when $$r=2.5$$, the original equation $$12r=30$$ holds true.