The given expression ;
[tex]d-\frac{c}{7}[/tex]for c = 28 and d = 21
Substitute the value of c = 28 and d = 21 in the given expression;
[tex]\begin{gathered} d-\frac{c}{7}=21-\frac{28}{7} \\ d-\frac{c}{7}=21-4 \\ d-\frac{c}{7}=17 \end{gathered}[/tex]Thus, the value of expression at c= 28 and d =21 is 17
Answer: 17
