Answer: 22
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Step-by-step explanation:
The triangles are similar, so we know the corresponding sides form ratios that are equal.
Note how...
FS and ZD are the first two letters of FSB and ZDR respectively
FB and ZR are the first & last letters of FSB and ZDR respectively
Based on those two facts above, we can form this proportion
FS/ZD = FB/ZR
38/15.2 = 55/x
Solve for x
38/15.2 = 55/x
38*x = 15.2*55
38*x = 836
x = 836/38
x = 22