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.10
C. 21
D. 38
Let x be the number of courses worth 3 credits and y be the number of courses worth 4 credits.
From the given information, we have the following two equations:
x + y = 16 (equation 1)
3x + 4y = 54 (equation 2)
Solving equation 1 for x, we get:
x = 16 - y
Substitute x = 16 - y into equation 2:
3(16 - y) + 4y = 54
48 - 3y + 4y = 54
48 + y = 54
y = 6
Now substitute y = 6 back into equation 1:
x + 6 = 16
x = 10
Therefore, the student completed 10 courses worth 3 credits. So the answer is:
B. 10