F.1 Math questions

Please to solve the following questions

1) Subtract the sum of the prime numbers between 10 to 20 from the sum of the
first 3 common multiples of 3 and 4. Find the result.
72-60=12 (Is it correct?)


2) A number of sweets are divided among four girls, Mary, Grace, Helen and
Mabel. Marys gets 4/15 of the sweets and Grace gets 3/10. The rest is
divided equally between Helen and Mabel. What fractions of the sweets
does Mabel get?


3) A test paper with maximum marjs 80 has 10 questions carrying equal marks.
For every wrong answer and blank answer the student will lose 5 marks and
3 marks respectively. Find the total mark for a student who has attempted 9
questions in which 6 are correct and 3 are wrong.