Answer:
∠B = 65°; ∠C = 115°
Step-by-step explanation:
The first thing you to do is set ∠B and ∠D equal to each other.
[tex]3n+20=6n-25[/tex]
The reason you do this is because the oppisite angles are equal to each other in a parallelogram.
Next, you want to start simplifying the equation (I personally like to start with the variables).
[tex]....3n+20=6n-25\\-3n.....-3n[/tex]
Then, you simplify again (you can combined these if you want but for example I am breaking it down more.
[tex]....20=3n-25\\+25.......+25\\....45=3n[/tex]
Then you dived by 3, and you get 15=n. Now (and people often forget this step) you have to plug it back in to solve for the equartion. ∠B=3(15)+20, ∠B=65. Now you have to subtract 65 from 180 because ∠B and ∠C are completmtry. 180-65=115=∠C
