Question

Cass drove 3 miles to school, and then she drove m miles to a friend's house. The total mileage for these two trips was 8 miles. Which equation CANNOT be used to determine the number of miles Cass drove?

A. 3 + m = 8
B. 3 - m=8
C.8 - 3 m
D. 8 - m=3

Answer 1

The equation that CANNOT be used to determine the number of miles Cass drove is option B: 3 - m = 8. The correct equation to determine the number of miles Cass drove is option D: 8 - m = 3.

Step-by-step explanation:

The equation that CANNOT be used to determine the number of miles Cass drove is option B: 3 - m = 8.

This equation subtracts the unknown variable m from 3, and then sets it equal to 8. However, in the given problem, Cass drove 3 miles to school, so the distance already known is positive. Therefore, subtracting m from 3 will not give the correct answer.

The correct equation to determine the number of miles Cass drove is option D: 8 - m = 3. This equation subtracts m from 8, and then sets it equal to 3, which models the situation accurately.