Life expectancy is defined by the formula `(2SB)/(G)`, where S = shoe size, B = average monthly electric bill in dollars, and G = GMAT score, If Melvin's GMAT score is twice his monthly electric bill, and his life expectancy is 50, what is his shoe size?

Answer

To solve the problem, we will follow the steps outlined below:

**Step 1: Understand the formula and the variables.**
The life expectancy \( L \) is given by the formula:
\[ L = \frac{2SB}{G} \]
where:
- \( S \) = shoe size
- \( B \) = average monthly electric bill in dollars
- \( G \) = GMAT score

**Step 2: Identify the given values.**
From the problem, we know:
- Melvin's life expectancy \( L = 50 \)
- Melvin's GMAT score \( G \) is twice his monthly electric bill \( B \), which can be expressed as:
\[ G = 2B \]

**Step 3: Substitute the known values into the formula.**
Substituting \( L = 50 \) into the formula, we have:
\[ 50 = \frac{2SB}{G} \]

**Step 4: Replace \( G \) with \( 2B \).**
Since \( G = 2B \), we can substitute this into the equation:
\[ 50 = \frac{2SB}{2B} \]

**Step 5: Simplify the equation.**
The \( 2B \) in the numerator and denominator cancels out:
\[ 50 = S \]

**Step 6: Solve for \( S \).**
From the simplified equation, we find that:
\[ S = 50 \]

Thus, Melvin's shoe size is \( 50 \).

### Final Answer:
Melvin's shoe size is \( 50 \).

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