Question

28 + ___ = 11 + 21

Explanation:

Step1: Calculate right - hand side sum

First, we need to find the value of the right - hand side of the equation \(11 + 21\). According to the addition operation, \(11+21 = 32\).

Step2: Solve for the unknown number

Let the unknown number be \(x\). The equation is \(28 + x=32\). To find \(x\), we use the subtraction operation. We know that \(x = 32-28\). Calculating \(32 - 28\), we get \(x = 4\).

Answer:

\(4\)