Answer
War: 124 million
Famine: 111 million
Tobacco: 71 million
Work Step by Step
Let's note:
$w$=war
$f$=famine
$t$=tobacco
We can write the system:
$\begin{cases}
w+f+t=306\\
w-f=13\\
w-t=53
\end{cases}$
We will use the substitution method. Solve Equation 2 and Equation 3 for $f$ and $t$:
$\begin{cases}
w+f+t=306\\
f=w-13\\
t=w-53
\end{cases}$
Substitute the expressions of $f$ and $t$ in Equation 1 to determine $w$:
$w+w-13+w-53=306$
$3w-66=306$
$3w=306+66$
$3w=372$
$w=\dfrac{372}{3}$
$w=124$
Substitute the value of $w$ in the expressions of $f$ and $t$:
$f=w-13$
$f=124-13$
$f=111$
$t=w-53$
$t=124-53$
$t=71$
The system's solution is:
$(124,111,71)$
