Solve the Mixed Number Equation: 2½ + ? = 4

To solve this problem, let's follow these steps:

• Step 1: Convert the mixed number $2\frac{1}{2}$ into an improper fraction.
• Step 2: Write and solve the equation by subtracting $\frac{5}{2}$ from 4.
• Step 3: Convert the result back to a mixed number, if needed.

Step 1: Convert $2\frac{1}{2}$ to an improper fraction: $2\frac{1}{2} = 2 + \frac{1}{2} = \frac{4}{2} + \frac{1}{2} = \frac{5}{2}.$

Step 2: Set up the equation $\frac{5}{2} + x = 4.$ Subtract $\frac{5}{2}$ from both sides: $x = 4 - \frac{5}{2}.$ Convert 4 to a fraction with denominator 2: $4 = \frac{8}{2}.$ Then we have $x = \frac{8}{2} - \frac{5}{2} = \frac{3}{2}.$

Step 3: Convert the improper fraction back to a mixed number: $\frac{3}{2} = 1\frac{1}{2}.$

Therefore, the solution to the problem is $1\frac{1}{2}$, which matches choice 3.