To get exactly 10% minerals, the mixture must consist solely of ingredients with 10% minerals, because any ingredient with <10% minerals will lower the overall mineral content below 10%.
Ingredients with 10% minerals: O and Q.
Mixing O and Q in any proportion yields exactly 10% minerals and exactly 30% protein (since both have 30% protein). The protein requirement (≥30%) is satisfied exactly.
No other pair or combination of at least two ingredients can achieve 10% minerals. For example, mixing O or Q with any other ingredient reduces mineral% below 10%. Three or more ingredients cannot reach 10% because no ingredient has >10% minerals.
Thus, only one way exists: mixing O and Q.
| Ingredient | Minerals% |
|---|
| O | 10 |
| P | 0 |
| Q | 10 |
| R | 5 |
| S | 5 |