Final answer:
To find the total number of houses visited, divide the number of houses that gave out M&Ms (20) by the percentage as a decimal (0.40). The calculation reveals that the student visited 50 houses.
Step-by-step explanation:
The question asks us to determine the total number of houses a student went to based on the percentage that gave out M&Ms. If 40% of the houses gave out M&Ms and the student received M&Ms from 20 houses, we first represent 40% as a decimal, which is 0.40. To find the total number of houses, we use the equation:
Number of houses visited = Number of houses that gave out M&Ms / 0.40
Substituting 20 for the number of houses that gave out M&Ms, we get:
Number of houses visited = 20 / 0.40
So, the total number of houses visited is:
Number of houses visited = 50 houses.
This means the correct answer is (a) 50 houses.