Find the Sum: Solving the Expression 28+45

To determine an expression equivalent to $28 + 45$, let us consider adjusting the components to make calculations easier while maintaining equivalence.

(1) Start with the original problem: $28 + 45$.

(2) To simplify, notice that we want to make a decomposition that doesn't change the sum. Increase 28 by 2, making it 30, which is easier to work with. However, you have to subtract 2 to balance the increase. So, the expression becomes:

$30 + 45 - 2$

(3) Compute within this adjusted equation:

• $30 + 45 = 75$
• $75 - 2 = 73$

(4) Checking the original unaltered computation:

• $28 + 45 = 73$

Both computations yield $73$, verifying their equivalence.

Thus, the alternative expression for $28 + 45$ that maintains equivalence is $30+45-2$, which corresponds to choice 4.