Q = -60 and P ≠ 32 will result in an equation with no solutions. (Both conditions must be met.)
_____
For Q = -60 and P = 32, there will be an infinite number of solutions. For any other values of Q and P, the solution is
.. x = (32 -P)/(Q +60)
Cos (B) = (a^2 + c^2 -b^2) / (2 * a * c)
cos (B) = (11^2 +17^2 -12^2) / (2 * 11 * 17)
cos (B) = (121 + 289 -144) / (374)
cos (B) = 266 / 374
cos (B) =
<span>
<span>
<span>
0.7112299465
Angle B = </span></span></span>44.665 degrees
The first equation given 
We have to add 1 and 5 to the right side first. We will get,

To get rid of 6 from the right side we have to subtract 6 from both sides.



To find n we have to move -2 to the other side by dividing both side by -2.



So we have got the required answer for the first question.
The solution is n = 0.
The second equation given,

First we have to move 7x to the left side by subtracting it from both sides.



Now we have to move -2 to the right side by adding 2 to both sides.



We have got the required answer for the second question.
The solution is x = -7.
The third equation given,

We have to get rid of that negative sign from both sides. As we have negative sign to both sides we can cancel it out. We will get,

Now we have to move 4 to left side by subtracting it from both sides.




So we have got the required answer .
The solution is x = 4.
By definition, we have

So, we have to solve two different equations, depending of the possible range for the variable. We have to remember about these ranges when we decide to accept or discard the solutions:
Suppose that 
In this case, the absolute value doesn't do anything: the equation is

We are supposing
, so we can accept this solution.
Now, suppose that
. Now the sign of the expression is flipped by the absolute value, and the equation becomes

Again, the solution is coherent with the assumption, so we can accept this value as well.