Problem 4 For each equation, draw a tape diagram and find the unknown value. \( \begin{array}{ll}\text { a. } x+9=16 & \text { b. } 4 \cdot x=28\end{array} \)

For the equation \(x + 9 = 16\), you can create a tape diagram that shows one segment representing \(x\) and another segment representing \(9\) next to it, with a total length of \(16\). To find the unknown \(x\), simply subtract \(9\) from \(16\). So, \(x = 16 - 9 = 7\). In the case of \(4 \cdot x = 28\), draw a tape diagram with four equal segments, representing \(x\), that altogether sum up to \(28\). To find \(x\), divide \(28\) by \(4\). Thus, \(x = \frac{28}{4} = 7\). Both equations reveal that \(x = 7\)!