Question

Help me please I'm really not able to get this

Answer 1

The area of a triangle is half that of the square around it, so in this case that would be:
$0.5 \times (8 \times 7) = 28$
The formula for the volume is:
$v = b \times h$
This leads to:
$224 = 28 \times h \\ h = 224 \div 28 = 8$

Answer 2

Hey!
No problem if you don't understand. Hopefully you will after this!
So we know the base lengths and we know that B is the area of the base. Here is how we would set it up.
V = ((b*h)/2) * h
That's the volume of this triangular prism because the triangle is the base and the area of a triangle is (b*h)/2. 
Now we can fill the variables in.
224 = ((8*7)/2) * h
Solve for the area of the base
224=28h
Now you want to get h alone because that is what you are solving for. Sadly, 28 is multiplied to it so what can we do? We would divide 28 on both sides, getting us:
h = 8

We can check if that's right!
V = ((8*7)/2) * 8
V = 28 * 8 
V = 224
That's right!
So H is 8
Hope this helps!