For this case we have the following system of equations:

We can write a system of equivalent equations.
For this, it is enough to multiply one of the two equations by a scalar.
Multiplying the equation 1 by 2, we have:

Therefore, the new system of equations is:

Answer:
A system that is equivalent is:
D) 
X = 3/2, -4
Get yourself a graphics calculator :)
Well first you need to find the LCM (least common multiple) of 4 and 6 (the denominators) so that you can subtract them from each other.
4: 4,8,12,16,20
6: 6, 12, 18, 24
The LCM is 12.
Now we can subtract the two mixed numbers by turning them into improper fractions.
5 3/12 -> 27/12
3 10/12 -> 42/12
42-27=15
The fraction is 15/12, which simplifies into 1 1/4.
She cut off 1 1/4 feet of the board.