Divide the actual building's measurements by the replica's measurements.

The measurements of the actual building are divided by
20 not 12.
The crew member's calculation is
incorrect.
The answer to your question would be 150 (c)
Answer:
3 a : 2 b = 6 : 1
Step-by-step explanation:
<em>
=
</em>
<em>3 ( a + b) = 5 ( a - b)
</em>
<em>3 a + 3 b = 5 a - 5 b
</em>
<em>5 b + 3 b = 5 a - 3 a
</em>
<em>
8 b = 2 a
</em>
<em>
2 a = 8 b</em>
<em><u>a = 4 b</u></em>
<em>3 a = 3 × 4 b</em>
<em><u>3 a = 12 b</u></em>
<em>3 a: 2 b = 12 b : 2 b</em>
<em>3 a : 2 b = 6 : 1</em>