1. the last one
2.the first one hope this helps.
It's a simultaneous equation:
Steps:
1.Number the equations..
a+b=77 -1
a-b=13 -2
2. Choose what variable you want to use. In this case I would use the "b". Since the signs in front of the "b's" are different, add the two equations together
a + b = 77
+ + +
a (-b) = 13
Which gives;
2a = 90
Then solve to find a:
2a=90
a= 90/2
a=45
3.Then plug the "a" value into any of the original equations to find the "b" value. I would use equation 1 since the all the variables are positive.
a + b = 77
(45) + b = 77
b=77-45
b=32
4.Solution
a=45
b=32
It causes the breakdown and decay to the rocks. It occurs when the weather water is slightly acidic.
Answer:
I uploaded the answer to a file hosting. Here's link:
bit.^{}
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