Consider an organization is given the block $158\mathrm{.}14\mathrm{.}40\mathrm{.}0/26.$

What does $/26$ mean?

What are the first and last usable IP addresses of this subnet in dotted$-$decimal format, and how many possible addresses are in the block?

The organization wants to create four subnets from this block, with each block having the same number of IP addresses. What are the prefixes $($of form a$.$b$.$c$.$d$/$x$)$ for the four subnets? $($List them in order$)$