Substituting the given values for b and c into the equation for abc,
a(-2 + 3i)(1 + 2i) = -37 + 36i
Multiplying out the terms in brackets,
a(-2 - 4i + 3i - 6) = -37 + 36i
Collecting like terms and multiplying through by -1,
a(8 + i) = 37 - 36i
The complex number a can be represented as m + ni, where m and n are constants we need to find.
(8 + i)(m + ni) = 37 - 36i
Multiplying out the terms in brackets,
8m + 8ni + mi - n = 37 - 36i
Collecting like terms and equating the real and imaginary parts, we end up with two simultaneous equations for m and n.
8m - n = 37 (from real part)
8n + m = -36 (from imaginary part)
Rearranging the first equation, we find that n = 8m - 37. Substituting this into the second equation,
8(8m - 37) + m = -36
64m - 296 + m = -36
65m - 296 = -36
65m = 260
m = 4
Subsituting this value for m back into the second equation,
8n + 4 = -36
8n = -40
n = -5
Putting it all together,
a = 4 - 5i
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