# CBSE NCERT Solutions for Class 7 Chapter 9

NCERT solutions can also prove to be of valuable help to students in their assignments and preparation of boards and competitive exams. Students get complete and tailored answers for each question in the NCERT textbooks.

**CBSE NCERT Solutions for Class 7 Maths Chapter 9:**

*Question-1*:

Find the sum:

(i) 5/4 + (-11/4 )

(ii) 5/3 + 3/5

(iii) -9/10 + 22/15

(iv) -3/ -11 + 5/9

(v) -8/19 + (-2) /57

(vi) -2/3 + 0

(vii) -2 1/3 + 4 3/5

*Solution*:

(i) 5/4 + (-11/4 ) =(5-11)/4 = -6/4 = -3/2

(ii) 5/3 + 3/5 =(5/3)*(5/5) + (3/5)*(3/3) = 25/15 + 9/15 [L.C.M. of 3 and 5 is 15]

=(25+9) / 15 = 34/15 = 2 4/15

(iii) -9/10 + 22/15 =(-9/10) *(3/3) + (22/15) * (2/2) = -27/30 + 44/30 [L.C.M. of 10 and 15 is 30]
= (-27+44) / 30 = 17/30
(iv) -3/ -11 + 5/9 = (-3/ -11)* (9/9) + (5/9) *(11/11) = 27/99 + 55/99 [L.C.M. of 11 and 9 is 99]

=(27+55) /99 = 82/99

(v) -8/19 + (-2) /57 =(-8/19) *(3/3) + (-2/57) *(1/1) = -24/57 + (-2)/57 [L.C.M. of 19 and 57 is 57]

= (-24 -2 ) / 57 = -26 / 57

(vi) -2/3 + 0 = -2/3

(vii) -2 1/3 + 4 3/5 = -7/3 + 23/5 = (-7/3) *(5/5) + (23/5) *(3/3)

= -35/15 + 69/15 [L.C.M. of 3 and 5 is 15]

=(-35 + 69) /15

= 34/15 = 2 4/15

*Question-2*:

Find :

(i) 7/24 - 17/36

(ii) 5/63 - (-6/21 )

(iii) -6/13 - (-7/15 )

(iv) -3/8 - 7/11

(v) -2 1/9 -6

*Solution*:

(i) 7/24 - 17/36 = (7/24) * (3/3) - (17/36) * (2/2) = 21/72 - 34/72 [L.C.M. of 24 and 36 is 72]

21/72 - 34/72 =(21- 34) /72 = -13 / 72

(ii) 5/63 - (-6/21 ) =(5/63)* (1/1) - (-6/21 ) *( 3/3) = 5/63 - (-18)/63 [L.C.M. of 63 and 21 is 63]

[L.C.M. of 63 and 21 is 63]

5/63 - (-18)/63 = (5- (-18)) /63 = (5+18 )/ 63 = 23/63

(iii) -6/13 - (-7/15 ) = (-6 /13 ) *(15/15 ) - ( -7 /15) * ( 13/13 ) = -90 / 195 - (-91/195)
[L.C.M. of 13 and 15 is 195]
-90 / 195 - (-91/195) = (-90 – (-91) )/195 = ( -90+91)/ 195 = 1/ 195
(iv) -3/8 - 7/11 = ( - 3/8) * ( 11/11) - (7/11) * (9/9) = -19/9 - 54/9 = (-19 – 54)/9 = -73 /9 = -8 1/9

*(8/8) = -33/88 - 56/88 [L.C.M. of 8 and 11 is 88] [L.C.M. of 8 and 11 is 88] -33/88 - 56/88 = (-33 – 56 )/88 =-89/88 = -1 1/88 (v) -2 1/9 -6 = -19/9 - 6/1 = (-19/9) * (1/1) – (6/1)*(9/9) [L.C.M. of 9 and 1 is 9] [L.C.M. of 9 and 1 is 9] (-19/9) * (1/1) – (6/1)