The table shows income tax rates. Marylinnet paid Ksh 4313 net tax/month. Her monthly taxable allowances were Ksh 15,220 and relief was Ksh 1,062. Deductions: NHIF Ksh 320, Union Ksh 200, Sacco Ksh 50

Kodi Kuu = Kodi Halisi (Net Tax) + Msamaha wa Kodi (Tax Relief)

$$\text{Kodi Kuu} = \text{Ksh } 4313 + \text{Ksh } 1062 = \text{Ksh } 5375$$

• Kodi katika bendi ya kwanza (10%):

$$10\% \text{ ya } 9680 = 0.10 \times 9680 = \text{Ksh } 968$$

Kodi iliyobaki = $5375 - 968 = \text{Ksh } 4407$

• Kodi katika bendi ya pili (15%): Kiwango cha mapato katika bendi hii = $18800 - 9680 = \text{Ksh } 9120$

$$15\% \text{ ya } 9120 = 0.15 \times 9120 = \text{Ksh } 1368$$

Kodi iliyobaki = $4407 - 1368 = \text{Ksh } 3039$

• Kodi katika bendi ya tatu (20%): Kiwango cha mapato katika bendi hii = $27920 - 18800 = \text{Ksh } 9120$

$$20\% \text{ ya } 9120 = 0.20 \times 9120 = \text{Ksh } 1824$$

Kodi iliyobaki = $3039 - 1824 = \text{Ksh } 1215$

• Kodi katika bendi ya nne (25%): Kodi iliyobaki (Ksh 1215) inatozwa katika bendi hii. Kiasi cha mapato kilichotozwa kodi katika bendi hii = $\frac{1215}{0.25}$

$$\text{Kiasi cha mapato} = \text{Ksh } 4860$$

Jumla ya Mapato Yanayotozwa Kodi (Total Taxable Income) = Mapato ya bendi 1 + Mapato ya bendi 2 + Mapato ya bendi 3 + Mapato yaliyotozwa kodi katika bendi ya 4

$$\text{Jumla ya Mapato Yanayotozwa Kodi} = 9680 + 9120 + 9120 + 4860$$ $$\text{Jumla ya Mapato Yanayotozwa Kodi} = \text{Ksh } 32780$$

Jumla ya Mapato Yanayotozwa Kodi = Mshahara wa Msingi + Posho Zinazotozwa Kodi

$$32780 = \text{Mshahara wa Msingi} + 15220$$ $$\text{Mshahara wa Msingi} = 32780 - 15220$$ $$\text{Mshahara wa Msingi} = \text{Ksh } 17560$$

Marylinnet's monthly basic salary is $\boxed{\text{Ksh } 17560}$.