\[b = |5 + a|\]
\[a = - 5:\]
\[b = \left| 5 + ( - 5) \right| = |5 - 5| = |0| = 0.\]
\[a = 0:\]
\[b = |5 + 0| = |5| = 5.\]
\[a = 4:\]
\[b = |5 + 4| = |9| = 9.\]