Question

5)\\
-4s + 2t - 13 = 0\\
8s - 6t = 42

Explanation:

Step1: Rewrite first equation

$-4s + 2t = 13$

Step2: Multiply first equation by 2

$2(-4s + 2t) = 2\times13$
$\implies -8s + 4t = 26$

Step3: Add to second equation

$(-8s + 4t) + (8s - 6t) = 26 + 42$
$\implies -2t = 68$

Step4: Solve for $t$

$t = \frac{68}{-2} = -34$

Step5: Substitute $t$ into first equation

$-4s + 2(-34) = 13$
$\implies -4s - 68 = 13$
$\implies -4s = 81$
$\implies s = -\frac{81}{4}$

Answer:

$s = -\frac{81}{4}$, $t = -34$