Can you please help me with this maths.?

Question

This ywer 75% of the graduating class of harriet school had taken at least 8 math course. of the remaining class members, 60% had taken 6 or 7 math courses. What percent of the graduating class had taken fewer than 6 math courses?

A total of 50 juniors and seniors were given a mathemathics test. The 35 juniors attained an average score of 80 while the 15 seniors attained an average of 70. what were the average score for all 50 students who took the test.

what is the sum of the polynomials
3(a square)b+2(a square)(b square) and - a(b square) + (a square)(b square) ?

Answer 1

25% of the school took less than 8 maths courses. and 40% of that 25% took less than 6 courses; so the answer is 40% x 25% = 10%

The total score of the juniors was 35 x 80 = 2800; the total score of the seniors was 15 x 70 = 1050; so the score of all the people taking the test was 1050+2800 = 3850.
50 people took the test, so the average score is 3850/50 = 77.

3aab+2aabb-abb+aabb =
3aab+3aabb-abb =
ab(3a+3ab-b)

Answer 2

The fraction of students who have taken maths is
3/4 + 3/5.1/4 = 15/20 + 3/20 = 18/20 = 90/100 = 90%.
Therefore, the percentage who have taken less than 6 courses is 10%

Total score of the juniors is 35 x 80, total score of seniors is 15 x 70. Sum of these scores is 2800 + 1050 = 3850. So average score is 3850/50 = 77.

3 a^2.b + a^2 b^2 - a b^2

Answer 3

1. We are left with 40% remaining of the 25% remaining. This would be 10%.

2. You need a weighted average. Total score of all students divided by total of students. (35*80 + 15*70) / (50) = 77

3. You may only add when both a and b are of the same power.
3(a square)b + 3(a square)(b square) + -a(b square)

Answer 4

1. 10%