Final answer:
The number of students taking Mandarin will never equal the number taking French.
Step-by-step explanation:
To determine when the number of students taking Mandarin will equal the number taking French, we need to set up an equation using the given information.
Let 'y' represent the number of years.
The equation for the number of students taking Mandarin is 20 + 4y, and the equation for the number of students taking French is 12 - 5y.
To find when these numbers are equal, we set up the equation:
20 + 4y = 12 - 5y.
Next, we solve the equation:
20 + 4y = 12 - 5y
Combine like terms:
9y = -8
Divide by 9:
y = -8/9
The number of years cannot be negative, so there is no solution to this equation. Therefore, the number of students taking Mandarin will never equal the number taking French under the given conditions.