Ganita Prakash class 6 Cbse Ncert syllabus book year 2024 to 2025 new syllabus chapter 7 fractions exercise no : 7.8 Explained the concepts of comparing fractions LCM method explained Subtraction with same denominators Subtraction with different denominators explained the concepts of fraction, fractional units, lowest term and Brahmagupta's method of adding and subtracting fractions page number from 180 to 182 all addition sums explained chikki concepts solved