Since you have y alone on one side of the equation......
Use substitution and plug in 1/2x-4 for y in the other equation.

Distribute

Combine like terms

Add 8 to both sides

Divide by 4
and 
Plug this value in for x

Simplify

Multiply everything by 8 and simplify

Divide.....

Your answers are:

Answer:
y= (x-2)^2/4-7
Step-by-step explanation:
Given :
Hight of the van from the ground, h = 3 feet.
The ramp into the van makes a 12° angle with the ground.
To Find :
How long is the ramp.
Solution :
Let, length of ramp is l .
So, height of ramp in terms of length is given by :

Hence, this is the required solution.
Y = - x + 4 that’s the answer hope it helps
The 2 numbers required are 13*8 and 14 * 8
that is 104 and 117