Answer:
4200$
Explanation:
If the store bought 300 toys at the cost of 10$, then the store spent 3000$.
We now know that 3000$ is 100%. To find 40% and to add that to 3000$, we must create the equation;
40/100x3000=1200$
All the toys were sold at 4200$, and the store profited 1200$.