91Ó°ÊÓ

Find: $$1-2+3-4+5-6+\ldots+99-100$$

Explain the error made below in simplifying \(\frac{15}{45}\) $$ \frac{15}{45}=\frac{3 \cdot 5}{3 \cdot 3 \cdot 5}=\frac{0}{3}=0 $$

To determine the average afternoon wait time in security lines at an airport, officials monitored four passengers, each at a different gate. The time that each passenger entered a security line and the time the same passenger cleared the checkpoint was recorded, as shown below. Find the average (mean) wait time for these passengers. $$ \begin{array}{|l|c|c|} \hline & {\text { Time }} & {\text { Time }} \\ \hline & {\text { entered }} & {\text { cleared }} \\ \hline \text { Passenger at Gate A } & {3: 05 \text { pm }} & {3: 21 \text { pm }} \\ \hline \text { Passenger at Gate B } & {3: 03 \text { pm }} & {3: 13 \text { pm }} \\ \hline \text { Passenger at Gate C } & {3: 01 \text { pm }} & {3: 09 \text { pm }} \\ \hline \text { Passenger at Gate D } & {3: 02 \text { pm }} & {3: 16 \text { pm }} \\ \hline \end{array} $$

Simplify each expression, if possible. $$ a+a+a $$

Find the LCD for \(\frac{5}{12}\) and \(\frac{1}{15}\)

To multiply two fractions, must they have like denominators? Explain.

Simplify each expression, if possible. $$ t-t-t-t $$

\(\text { Simplify: } \frac{3 \cdot 3 \cdot 5}{3 \cdot 5 \cdot 5 \cdot 11}\)

Simplify each expression, if possible. $$ 60\left(\frac{3}{20} r-\frac{4}{15}\right) $$

Evaluate: \(\left(\frac{2}{3}\right)^{3}\)