Update file README.md

sheets/03_card_sat/README.md

@@ -18,8 +18,8 @@ Such a formula has the following form:
 ```
 
 The $\ell_{i,j}$ are so called *literals* and have either the  form $x_u$ or $\bar{x}_u := \neg x_u$,  i.e., they are either a variable or a negation of it.
-The formula $\phi$, thus, is a conjunction (AND-connections) of clauses, which are disjunction (OR-connections) of variables or negated variables. 
-And example for such a formula would be
+The formula $\phi$, thus, is a conjunction (AND-connections) of clauses, which are disjunctions (OR-connections) of variables or negated variables. 
+An example for such a formula would be
 ```math
 \phi_1 = (x_1 \vee \bar{x}_2 \vee x_3) \wedge (x_2 \vee x_4).
 ```