to check if the expressions are equivalent simplify the expression that is not simplified and see if the results are equivalent
for the first one
[tex]\begin{gathered} 4(5c+3)=9c+7 \\ 20c+12\ne9c+7 \end{gathered}[/tex]the expressions are not equivalent
second expression
[tex]\begin{gathered} 10f-10=2(8f-5) \\ 10f-10\ne16f-10 \end{gathered}[/tex]the expressions are not equivalent
third expression
[tex]\begin{gathered} 12g+21=3(4g+7) \\ 12g+21=12g+21 \end{gathered}[/tex]the expressions are equivalent
forth expression
[tex]\begin{gathered} 6(4j-6)=24-36j \\ 24j-36\ne24-36j \end{gathered}[/tex]expressions are not equivalent
