7. In Mr. Laub's class, there are 28 students, of which, the number of girls is 4 more than the number of boys. Then, the ratio of the number of girls to the number of boys in the class is ( ).
(A) $3: 4$
(B) $4: 3$
(C) $3: 2$
(D) $7: 4$
(E) $2: 1$
7. B.

Let the number of girls be $x$, and the number of boys be $y$. Then
$$
\begin{array}{l}
\left\{\begin{array} { l } 
{ x - y = 4 , } \\
{ x + y = 28 }
\end{array} \Rightarrow \left\{\begin{array}{l}
x=16, \\
y=12
\end{array}\right.\right. \\
\Rightarrow \frac{x}{y}=\frac{16}{12}=\frac{4}{3} .
\end{array}
$$