Answer:
x = 60 cm
Explanation:
If we assume the figures are similar, then corresponding sides are proportional.
x/36 = 35/21
x = 36(35/21) = 60 . . . . cm
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You can consider the ratios of side lengths. Shortest to longest, they are ...
7 : 9 : 12 = 21 : 27 : 36 = 35 : 45 : 60
The smaller figure is 3 times the basic ratio; the larger figure is 5 times the basic ratio.