To solve for \( ? \) in the equation:
\[ \frac{28}{100} = \frac{?}{10} + \frac{8}{100} \]
First, we can consolidate the right side of the equation. To do that, we need a common denominator for the fractions. The common denominator between \( 10 \) and \( 100 \) is \( 100 \).
We can rewrite \( \frac{?}{10} \) with a denominator of \( 100 \):
\[ \frac{?}{10} = \frac{? \times 10}{100} = \frac{10?}{100} \]
Now we can rewrite the equation:
\[ \frac{28}{100} = \frac{10? + 8}{100} \]
Since the denominators are the same, we can set the numerators equal to each other:
\[ 28 = 10? + 8 \]
Next, we isolate \( 10? \) by subtracting \( 8 \) from both sides:
\[ 28 - 8 = 10? \] \[ 20 = 10? \]
Now, we can solve for \( ? \) by dividing both sides by \( 10 \):
\[ ? = \frac{20}{10} = 2 \]
Thus, the value for \( ? \) is:
\[ \boxed{2} \]