Answer:
left to right, we have t/u < r/s < p/q.
Explanation:
The properties of ordering tell you ...
if a > b and b > c, then a > c
Here, we have a = p/q, b = r/s, c = t/u. The same property still applies:
if p/q > r/s and r/s > t/u, then p/q > t/u
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On a number line, the largest value is on the right:
p/q is right of r/s
r/s is right of t/u
therefore, ...
p/q is right of t/u