(F/G)2-H; just simplify it.
This is a combination in which you choose 4 from 10.
The formula is
combinations = 10! / 4! * (10-4)!
combinations = 10! / 4! * 6!
combinations = 10 * 9 * 8 * 7 * 6! / 4! * 6!
combinations = 10 * 9 * 8 * 7 / 4 * 3 * 2
combinations = 10 * 3 * 7
combinations = 210
Source:
http://www.1728.org/combinat.htm
We know that ∠1 equals ∠3, from that we can find x:

The sum of ∠1 and ∠2 must equal 180°:

Since we already know x, we can solve for y:

Result: x=10, y=6
<h2>Figure 1</h2>
Answer: 350
Formula: W × H × L
7 × 5 × 10 = 350
<h2>Figure 2</h2>
Answer: 288
Formula: 

<h2>Figure 3</h2>
Answer: 14.7
Formula: 

<h2>Figure 4</h2>
Answer: 4.29
Formula: W × H × L
2.6 × 1.5 × 1.1 = 4.29
<h2>Figure 5</h2>
Answer: 60
Formula: W × H × L
4 × 3 × 5 = 60
<h2>Figure 6</h2>
Answer: 27.2
Formula: 

<h2>Figure 7</h2>
Answer: 
Formula: L × W × H

<h2>Figure 8</h2>
Answer: 86.4
Formula: 

Explanation: To find the volume for a rectangular prism, multiply the Length, Width and Height. To find the volume for a triangular prism, multiply the Base, Height and Length by 1/2.