\( \left. \begin{array} { l } { b a + 90 = 110 } \\ { \quad a = } \end{array} \right. \)

To solve for \( a \) in the equation \( ba + 90 = 110 \), first, isolate the term containing \( a \). Subtract 90 from both sides to get \( ba = 110 - 90 \), which simplifies to \( ba = 20 \). Now, to find \( a \), you can express it as \( a = \frac{20}{b} \). This indicates that the value of \( a \) depends on the value of \( b \). As you dive deeper into algebra, you might encounter different types of equations and variables. Remember, it's essential to keep equations balanced when isolating variables or making substitutions. This skill will help prevent common pitfalls, like inadvertently changing the value of the equation’s sides! So, always check your steps to ensure that your solutions are accurate.