A college student completed some courses worth 3 credits and some courses worth 4 credits. The student earned a total of 54 credits after completing a total of 16 courses.
How many courses worth 3 credits did the student complete
A- 3
B- 20
C-21
D-38
Let's say the student completed x courses worth 3 credits and y courses worth 4 credits.
According to the problem:
3x + 4y = 54
x + y = 16
We can solve this system of equations using substitution or elimination.
Let's use substitution:
x = 16 - y
Substitute x = 16 - y into the first equation:
3(16 - y) + 4y = 54
48 - 3y + 4y = 54
y = 6
Substitute y = 6 back into x = 16 - y:
x = 16 - 6
x = 10
Therefore, the student completed 6 courses worth 4 credits and 10 courses worth 3 credits.
Answer: A- 6 courses worth 3 credits.