Answer:
21
Step-by-step explanation:
Let n represent the number we're looking for. Then ...
n × (proteus length) = 3 × (palustris length)
n × 0.7 mm = 3 × 4.9 mm
n = (3 × 4.9 mm)/(0.7 mm) = 3 × 49/7 = 3 × 7
n = 21
You would have to line up 21 amoeba proteus to equal the length of three pelomyxa palustris.
