How do I calculate the percentage of Calculax in a vat after one hour?

Question

I have a problem that states:

A container has 250 gallons of solution that had 4% Calculax (per volume). Solution with 6% Calculax is pumped into the container at a rate of 10 gal/min and the mixture is pumped out at the same rate. What is the percentage of Calculax in the vat after an hour?

I am having difficulty trying to figure out how to start, especially the equation for it. Any help is appreciated. Thank you in advance!

Answer 1

There are $250\cdot4\%=10$ gallons of Calculax in the container initially. Every minute we add $10\cdot6\%=0.6$ gallons of Calculax every minute. After $1$ hour there are $10+0.6\cdot60$ gallons of Calculax in the container.

There are $250$ gallons of solution in the container initially. Every minute we add $10$ gallons of solution every minute. After $1$ hour there are $250+10\cdot60$ gallons of solution in the container.

Now divide the number of gallons of Calculax in the container by the number of gallons of solution in the container to get the fraction of Calculax. Then multiply by $100$ to get the percentage of Calculax in the solution. I'll leave the calculations to you.