Ok, so we know that RST is equal to 6x+12
And RST is also equal to 78 + 3x-12
so we set them equal to each other
6x + 12 = 3x - 12 + 78
And simplify
3x = 54
x = 18
Finally, we solve for the angle with 18 for x
6(18) + 12
108 + 12
120
Hope this helps
The answer you're looking for my good lad is C
A value equal to -(-3.7) is 3.7
The negative signs outside and inside zero out each other, which means you will get a positive. Think of (negative) as opposite. The opposite of an opposite will cancel out and give you what you had.
(x + 5)²z
(x + 5)(x+ 5)z
(x² + 5x + 5x + 25)z
(x² + 10x + 25)z
(x²)z + (10x)z + (25)z
x²z + 10xz + 25z