Rewrite the system of equations in matrix form.

This system has a unique solution
so long as the inverse of the coefficient matrix
exists. This is the case if the determinant is not zero.
We have

so the inverse, and hence a unique solution to the system of equations, exists as long as m ≠ -4.
The answer is the first answer is the first option.

The answer is equal to D.
Step-by-step explanation:
64/(1+1+2)
= 64/4
= 16
1 : 1 : 2
mark = 1×16 = 16
dave = 1×16 = 16
ralph = 2×16 = 32