Answer: 7
Step-by-step explanation: This is a adjacent angle, meaning they've a common vertex and side but don't overlap.
In the problem...
This is a right and acute angle. So, we can subtract 90 by 55 to find the value of x.
90 - 55 = 35. We're not done yet. In the problem, it says 5x. We'll need to divide 35 by 5 to get our answer.
35 ÷ 5 = 7
Hence, 7 is the answer.
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