7:28=5,5:4x

To solve the equation \(7:28 = 5:4x\), we start by rewriting the ratios as fractions:

\[ \frac{7}{28} = \frac{5}{4x} \]

Next, simplify the left side:

\[ \frac{7}{28} = \frac{1}{4} \]

Now we have:

\[ \frac{1}{4} = \frac{5}{4x} \]

Cross-multiplying gives us:

\[ 1 \cdot 4x = 4 \cdot 5 \]

This simplifies to:

\[ 4x = 20 \]

To find \(x\), divide both sides by 4:

\[ x = \frac{20}{4} = 5 \]

Thus, the solution is:

\[ \boxed{5} \]