Answer:
The cost of mixture is
![(12m + 30n)/(m+n)\text{ dollars per gallon}](https://img.qammunity.org/2021/formulas/mathematics/high-school/pebgcmc43v5gwucvm24trm4jchgb1o4mq5.png)
Explanation:
We are given the following in the question:
Cost of white per gallon = $12 a gallon
Amount of white paint in the mixture = m gallons
Total cost of white paint =
![12* m = 12m\$](https://img.qammunity.org/2021/formulas/mathematics/high-school/dfaf6yvbtol3fk4djq9arv904eo430apz3.png)
Cost of blue per gallon = $30 a gallon
Amount of blue paint in the mixture = n gallons
Total cost of blue paint =
![30* n = 30n\$](https://img.qammunity.org/2021/formulas/mathematics/high-school/t5h3rkskv21hnha6qmzds1y1xnhtxo2vck.png)
Total cost of mixture =
Total cost of white paint + Total cost of blue paint
![(12m + 30n)\text{ dollars}](https://img.qammunity.org/2021/formulas/mathematics/high-school/5d0z7449qgl1sycyx13widjy5qc9yr560a.png)
Total amount of mixture =
Amount of white paint in the mixture + Amount of blue paint in the mixture
![=(m+n)\text{ gallons}](https://img.qammunity.org/2021/formulas/mathematics/high-school/i5abw1x2g9wp4542rd0wnofbb0pacn8har.png)
Cost of mixture per gallon =
![=\frac{\text{Total cost}}{\text{Total amount}}\\\\=(12m + 30n)/(m+n)\text{ dollars per gallon}](https://img.qammunity.org/2021/formulas/mathematics/high-school/cegqort65ive9204qzsenmtfon4aky1wmj.png)
is the required cost of mixture.