Question

what e answer to 0.3(n-4)=15 ?

Answer 1

$\it 0.3(n-4)=15|_{\cdot{10}} \Longrightarrow 3(n-4) = 150 |_{:3} \Longrightarrow n-4 = 50 \Longrightarrow \\\;\\ \Longrightarrow n = 50+4 \Longrightarrow n=54$