Answer:
6
Step-by-step explanation:
Multiply 7x+3 by 2. When you get 14x+6, set equal to 90 and solve for x.
Trigonometry as taught is mostly about memorizing two lousy triangles, namely half a square and half an equilateral triangle. This one is half an equilateral triangle.
The respective opposite sides of the 30/60/90 triangle are in ratio 
A sine of √3/2 is an opposite of √3 and a hypotenuse of 2, so opposite and hypotenuse of the 60 degree angle. (It's the mama bear, in the middle, just right.)

In the end you just have memorize the two tired triangles of trig.
Answer:
The answer is -96
Step-by-step explanation:
The answer is -96
9514 1404 393
Answer:
B. ΔDEF ≅ ΔSRU
Step-by-step explanation:
Reflection changes corresponding vertices from CCW order to CW order. Vertex D gets reflected to (-6, 4), then translated to (-3, 0). After this transformation, its image is vertex S. The vertices in CW order from S are SRU. Hence, ΔDEF ≅ ΔSRU, matching choice B.