To find <ABC, the first thing you would need to do is to find angle DBA and the value of x
As <DBE is a right angle, <DBE is on the same straight line as well,meaning that it would be 90° , a right angle as well.
It also mean that the total sum of the angles unknown would be 90°
To find x,we need to set up an equation:
(2x+14)+ (x+7) = 90
3x+21 = 90
3x = 69
x = 23
Thus,<ABC would be
(23)+7
=30°
Hope it helps!
Answer:
45.8
Step-by-step explanation:
We need to find the surface area for this entire figure!
We can see that this is a pyramid here - we must find the area of the 3 triangles and the base triangle at the bottom.
The 3 triangles building up the pyramid are all equal to each other.
To find the area of a triangle, use 

Round to the nearest tenth: 45.75 -> 45.8
Step 1. Divide both side by 16
100/16 = 6t - 13
Step 2. Dimplify 200/16 to 25/2
25/2 = 6t - 13
Step 3. Add 13 to both sides
25/2 + 13 = 6t
Step 4. Simplify 25/2 + 13 to 51/2
51/2 = 6t
Step 5. Divide both sides by 6
51/2/6 = t
Step 6. Simplify 51/2/6 to 51/2 * 6
51/2 * 6 = t
Step 7. Simplify 2 * 6 to 12
51/12 = t
Step 8. Simplify 51/12 to 17/4
17/4 = t
Step 9. Switch sides
t = 17/4