<h3>Key points :-</h3>
᪥ The formula to find the 31st term is : 
᪥ In the formula,
represents the first term of the sequence.
᪥
is the number of terms, In our case n is 31.
᪥
is the common difference between the terms, In our case d is 4.

<em>Detailed Solution is attached</em>᭄
Answer:
12 combinations
Step-by-step explanation:
<span>A complex number is a number of the form a + bi, where i = and a and b are real numbers. For example, 5 + 3i, - + 4i, 4.2 - 12i, and - - i are all complex numbers. a is called the real part of the complex number and bi is called the imaginary part of the complex number.</span>