A taxpayer whose principal business in this State is (a) manufacturing or any form of collecting, buying, assembling, or processing goods and materials within this State, or (b) selling, distributing, or dealing in tangible personal property within this State, shall make returns and pay annually an income tax which includes its income apportioned to this State. Its income apportioned to this State is determined by multiplying the net income remaining after allocation under Sections 12-6-2220 and 12-6-2230 by a fraction, the numerator of which is the property ratio, plus the payroll ratio, plus twice the sales ratio, and the denominator of which is four. However, where the sales ratio does not exist, the denominator of the fraction is the number of existing ratios, and where the sales ratio exists but the payroll ratio or the property ratio does not exist, the denominator of the fraction is the number of existing ratios plus one. The property, payroll, and sales ratios must be determined in accordance with Sections 12-6-2260, 12-6-2270, and 12-6-2280, respectively.