Chemical Fertilizer Mixture Ratio

Let $a$ units of Alpha and $b$ units of Beta be taken. K comes only from Alpha. K in Alpha is $10\%$ and K in mixture is $6\%$. $10\% \times a = 6\% \times (a + b) \implies 0.04a = 0.06b \implies \frac{a}{b} = \frac{3}{2}$

Let $a = 3$ and $b = 2$. Let percentage of P in Beta be $p\%$. P in mixture: $3 \times 70\% + 2 \times p\% = 5 \times 68\%$ $210 + 2p = 340 \implies 2p = 130 \implies p = 65\%$

Since Beta contains only N and P, N in Beta = $100\% - 65\% = 35\%$. Ratio of N and P in Beta = $35\%$ and $65\%$.