Select the correct combination of mathematical signs to sequentially replace the* signs and balance the given equation.
74 * 34 * 78 * 23 * 23 * 30

The six numbers appear in the fixed order
$$74\;*\;34\;*\;78\;*\;23\;*\;23\;*\;30$$
so we need exactly five mathematical signs (the last one must be ‘’=’’) that make the statement true.

Testing Option A:
Insert $$\div, -, +, \times, =$$ ➔
$$74 \div 34 - 78 + 23 \times 23 = 30$$
$$2.176\ldots - 78 + 529 = 30$$ ⟹ false.

Testing Option B:
Insert $$+, \div, \times, -, =$$ ➔
$$74 + 34 \div 78 \times 23 - 23 = 30$$
The left-hand side is nowhere near 30. False.

Testing Option C:
Insert $$+, -, +, -, =$$ ➔
$$74 + 34 - 78 + 23 - 23 = 30$$

Now calculate step by step:
$$74 + 34 = 108$$
$$108 - 78 = 30$$
$$30 + 23 = 53$$
$$53 - 23 = 30$$
Hence the left-hand side equals 30, exactly matching the right-hand side. The equation is perfectly balanced.

Testing Option D:
Insert $$-, \div, +, \times, =$$ ➔
$$74 - 34 \div 78 + 23 \times 23 = 30$$
Again the values do not match 30. False.

The only sequence that balances the equation is Option C.

Option C which is: $$+, -, +, -, =$$