Step-by-step explanation:
[tex](9x + 24) + 30x = 180[/tex]
[tex]39x + 24 = 180[/tex]
[tex]39x = 156[/tex]
[tex]x = 4[/tex]
Hence，we know
<DEC
[tex] = 9x + 24 = 9 \times 4 + 24 = 60[/tex]
<AEB=<DEC=60
