Negatives in Two Steps

$5-2x = 11$ looks different because the unknown comes second, but the operations are the same. $x$ is multiplied by $-2$, and then 5 is added. Subtract 5 from both sides, then divide both sides by $-2$:

$$-2x = 6$$

$$x = -3$$

Check: $5-2\cdot \left(-3\right) = 5+6 = 11$, which is true.

Read $5-2x$ as $5-2x$. The coefficient of $x$ is $-2$, including its sign. Divide by $-2$, not by 2, and the answer comes out with the correct sign.