Answer:
I hope it will help you :)
The answer should be 31/10
<h2>

</h2>

◇◆□■□■□■□■□■□■□■□■□■□■□■□■□■□■□■□■□■□◆◇
x + 2x + 9y - 7y
3x + ( 9y - 7y )
3x + 2y
◇◆□■□■□■□■□■□■□■□■□■□■□■□■□■□■□■□■□■□◆◇

20/28 = 3x / (4x + 2)
84x = 20(4x + 2)
84x - 80x = 40
4x = 40
x = 10
so the 2 lines are equal to 30 and 42
It causes the breakdown and decay to the rocks. It occurs when the weather water is slightly acidic.