Addition with Tens and Units: Finding Components of 73

To solve this problem, we'll consider the decimal structure of the number 73, which involves tens and units:

• Step 1: Identify the tens digit in 73. The number 73 has 7 tens, corresponding to the number 70.
• Step 2: Identify the units digit in 73. The number 73 has 3 units, corresponding to the number 3.
• Step 3: Formulate the addition exercise using these components. The tens and units can be added as $70 + 3$.

Thus, the addition exercise using tens and units which results in 73 is $70 + 3$.

If we look at the provided choices, we see that choice 3 ($70 + 3$) correctly represents this breakdown.

Therefore, the solution to the problem is $70 + 3$.