Answer:
-6
Step-by-step explanation:
the x value is just plugging that number in for x so
-3x-8=10 (add 8 to both sides) so
-3x=18 (divide by -3 on both sides) so
x=-6

We know that, in ∆ABC,
∠A+∠B+∠C = 180°
But the triangle is right angled at C
ie., ∠C = 90°
Therefore, ∠A+∠B+ 90° = 180°
⇒ ∠A + ∠B = 90°
Therefore, <u>cos(A + B) = cos 90º = 0</u>
The GCF of 180 and 240 is 60