You have to formulate equations for this problem.
Let S = Science score
M = Math score
C =
Chemistry score
To illustrate the given:
0.9S = 0.75M
0.9S = 0.8C
You are given that Karen’s Math score is 96 marks. You have
to substitute the Math score to the first equation.
0.9S = 0.75(96)
0.9S = 72
S = 80
Therefore, Karen’s Science score is 80. Now, you have to
substitute the Science score to the second equation.
0.9(80) = 0.8C
0.8C = 72
C = 90
So, Karen’s Chemistry score is 90.
Therefore, the total score of the 3 subjects is 266 (96 + 80
+ 90).
