Solve the simultaneous equation 3m+ n=-5 m=1-3n

Step 1: Substitute the expression for $m$ from the second equation into the first equation.
From the second equation, we have:
$m = 1 - 3n$
Substituting into the first equation:
$3(1 - 3n) + n = -5$

Step 2: Expand and simplify the equation.
$3 - 9n + n = -5$
Combine like terms:
$3 - 8n = -5$

Step 3: Isolate $n$.
Subtract 3 from both sides:
$-8n = -5 - 3$
$-8n = -8$
Divide by -8:
$n = 1$

Step 4: Substitute $n$ back into the equation for $m$.
Using $m = 1 - 3n$:
$m = 1 - 3(1) = 1 - 3 = -2$

Final answers:
$\boxed{m = -2}$ and $\boxed{n = 1}$