diff --git a/flow/index.md b/flow/index.md
index c61b1ef..cf4c684 100644
--- a/flow/index.md
+++ b/flow/index.md
@@ -17,7 +17,7 @@ In this section, we introduce normalizing flows: a type of method that combines
 
 In normalizing flows, we wish to map simple distributions (easy to sample and evaluate densities) to complex ones (learned via data). The change of variables formula describe how to evaluate densities of a random variable that is a deterministic transformation from another variable.
 
-**Change of Variables**: $$Z$$ and $$X$$ be random variables which are related by a mapping $$f: \mathbb{R}^n \to \mathbb{R}^n$$ such that $$X = f(Z)$$ and $$Z = f^{-1}(X)$$. Then 
+**Change of Variables**: Let $$Z$$ and $$X$$ be random variables which are related by a mapping $$f: \mathbb{R}^n \to \mathbb{R}^n$$ such that $$X = f(Z)$$ and $$Z = f^{-1}(X)$$. Then 
 
 {% math %}p_X(\mathbb{x}) = p_Z(f^{-1}(\mathbb{x})) \left\vert \text{det}\left(\frac{\partial f^{-1}(\mathbb{x})}{\partial \mathbb{x}}\right) \right\vert