Okay, I'm actually going to help with this! c:
Okay, to find the answer you must set it up like this: 1x+5x=180. This is because these two angles add up to make up a supplementary angle, which, as you know, is 180. Now, I will show you the steps.
1. 1x+5x=180
2. Put the x into simpler form: 6x=180
3. Now divide 180 by 6 to isolate x. x=30.
But we're not done.
4. Plug 30 into the equation. 1(30)+5(30)=180.
Since you only need to find the larger angle, you'd multiply 5 by 30.
Your final answer is 150. Hoped this helped!