# How can I put both in the same line?

\textbf{BC Calculus - Step-by-Step
\begin{flushright}{Name \underline{\hspace{2.6in}}}\end{flushright}}

• You can't with flushright ... – user31729 Jan 2 '17 at 23:02
• Welcome to TeX.SE. Next time please provide complete small document (called MWE: Minimal Working Example), which we test without to complete your code sniped to it. – Zarko Jan 2 '17 at 23:23

flushright is a display enviornment that can't be used inline, also I made the underline shorter so it fits.

\documentclass{article}

\begin{document}

\noindent X\dotfill X

\noindent
\textbf{BC Calculus - Step-by-Step\hfill
Name \underline{\hspace{1.6in}}}
\end{document}