## Thinking Mathematically (6th Edition)

Let the number of years spent on sleeping be$S$. Let the number of years spent on eating be$E$. From the given first condition, we get the linear equation like, $S+E=32$ (I). From the second condition, we get the linear equation like: $S=E+24$ (II) By observing, these both equations are simultaneous linear equations. We can solve by substituting S in equation (I). By substituting we get: \begin{align} & E+24+E=32 \\ & 2E=8 \\ & E=4 \end{align} Substituting $E=4$ in equation (I) we get: \begin{align} & S+4=32 \\ & S=28 \end{align} By solving both equations, we get number of years spent in sleeping is 28 and number of years spend in eating is 4 years.