standard_description: Add and subtract fractions with unlike denominators (including mixed numbers) by replacing given fractions with equivalent fractions in such a way as to produce an equivalent sum or difference of fractions with like denominators. For example, 2/3 + 5/4 = 8/12 + 15/12 = 23/12. (In general, a/b + c/d = (ad + bc)/bd.)
problem_activity: Task
The Burj Khalifa (Dubai) is about 2$\frac{1}{2}$ times as tall as the Eiffel Tower (Paris) . The Eiffel Tower is about $\frac{5}{7}$ as tall as the Willis Tower (Chicago).
Which of these buildings is the tallest? Which is the shortest? Explain.
Draw pictures to illustrate.


aligns: no