[tex]\qquad\qquad\huge\underline{{\sf Answer}}[/tex]
Let's solve ~
[tex]\qquad \sf \dashrightarrow \: log_{5}(2x) = 4[/tex]
[tex]\qquad \sf \dashrightarrow \: 2x= {5}^{4} [/tex]
[tex]\qquad \sf \dashrightarrow \: 2x= 625[/tex]
[tex]\qquad \sf \dashrightarrow \: x= 625 \div 2[/tex]
[tex]\qquad \sf \dashrightarrow \:x = 312.5[/tex]
I Hope you understood the procedure ~