diff --git a/问题/均贫富.md b/问题/均贫富.md
index 439ce59..7bcbb83 100644
--- a/问题/均贫富.md
+++ b/问题/均贫富.md
@@ -8,7 +8,7 @@
 
 $
 \begin{aligned}
-a - x &= b + x &(a \in \Bbb{N}, b \in \Bbb{N}, a>b) \\\\
+a - x &= b + x &({a}\in\Bbb{N},{b}\in\Bbb{N},a>b) \\\\
 2x &= a - b  &(移项并交换等式两侧) \\\\
  x &= \dfrac{a-b}{2}  &(等式两侧同除以2)
 \end{aligned}