[tex]\displaystyle\bf\\~[474+3(4a-12)] : 19 = 30\\\\474+3(4a-12) = 30\times19\\\\474+3(4a-12) = 570\\\\3(4a-12) = 570-474\\\\3(4a-12) = 96\\\\(4a-12)=96:3\\\\4a-12=32\\\\4a=32+12\\\\4a=44\\\\a=44:4\\\\\boxed{\bf a=11}[/tex]
