Final answer:
Fred was assigned a total of 25 math problems to complete tonight. This was determined by using the proportion where 10 problems are equivalent to 40%, therefore, dividing 10 by 0.40 gives us the total number of problems.
Step-by-step explanation:
Fred completed 10 math problems, which represent 40% of the total number of problems he was assigned to complete tonight. To determine the total number of problems assigned, we can set up a simple proportion. Let x represent the total number of problems. Therefore, 40% of x (which is 0.40x) equals 10. Setting up the equation, we get 0.40x = 10. Dividing both sides by 0.40 gives us x = 10 / 0.40, which simplifies to x = 25. This means that Fred was assigned a total of 25 math problems to complete tonight.