Answer:
77
Step-by-step explanation:
Firstly, we need to calculate the total score of the junior students and the total score of the senior students.
The total score of the junior students is 35 * 80 = 2,800
The total score of the senior students is 15 * 70 = 1050
The total score is thus 2,800 + 1,050 = 3,850
The average score of the 50 students is thus 3,850/50 which equals 77
Answer:

Option D is the correct option.
Step-by-step explanation:

When there is a ( + ) in front of an expression in parentheses , there is no need to change the sign.
That means, the expression remains the same.
Just remove the unnecessary parentheses
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Collect like terms and simplify
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Hope I helped!
Best regards!!
all u do is see what looked right and add
LCM I believe. Because it’s every 6 days he does both