I didn’t get an answer that matches your answer choices, but here are mine:
exact form: p = 69/7
decimal form: p = 9.857142
mixed number form: p = 9 (6/7)
First, subtract 30x from each side to get:
-60 = -10x
Then, divide each side by -10 to get:
x = 6
Now, plug back in to check your answer:
30(6) - 60 = 20(6)
180 - 60 = 120
120 = 120
Hope this helps!! :)