New Learning Composite Mathematics Class 6 SK Gupta Anubhuti Gangal Algebra Chapter 7D Solution
(1) (a) 7 = a – 10 Add 10
(b) – 2 + x = 15 Add 2
(c) – 20 = m + 5 subtract 5
(d) 3n = 12 divide by 3
(e) 8 = 2y divide by 2
(f) 1/7 q = 3 multiply by 7
(2) (a) 7 + 10 = a – 10 + 10
∴ a = 17
(b) – 2 + x + 2 = 15 + 2
∴ x = 17
(c) – 20 – 5 = m + 5 – 5
∴ m = – 25
(d) 3n/3 = 12/3
∴ n = 4
(e) 8/2 = 2y/2
∴ y = 4
(f) 1/7 q X7 = 3X7
∴ q = 21
(3) (a) (i) x + 2 = 8
Or, x + 2 – 2 = 8 – 2
Or, x = 6
(ii) 6 = P + 5
Or, P + 5 – 5 = 6 – 5
∴ P = 1
(iii) x + 5 1/2 = 7 1/2
Or, x + 5 1/2 – 5 1/2 = 7 1/2 – 5 1/2
Or, x = 14/2 – 11/2
Or, x = 14 – 11/2
∴ x = 3/2
(iv) 6.5 = x + 4.3
Or, x + 4.3 – 4.3 = 6.5 – 4.3
Or, x = 2.2
(b) (i) y – 3 = 5
Or, y – 3 + 3 = 5 + 3
Or, y = 8
(ii) 8 = c – 3
Or, c – 3 + 3 = 8 + 3
Or, c = 11
(iii) 9/2 = m – 7/2
Or, m – 7/2 + 7/2 = 9/2 + 7/2
Or, m = 9+7/2
Or, m = 16/2
∴ m = 8
(iv) z – 10.7 = 1.3
Or, z – 10.7+10.7 = 1.3+10.7
Or, z = 12
(c) (i) 5x = 10
Or, 5x/5 = 10/5
∴ x = 2
(ii) 45 = 9t
Or, 9t/9 = 45/9
∴ t = 5
(iii) 0.2y = 3
Or, 0.2y/0.2 = 3/0.2
Or, y = 3X10/2
∴ y = 15
(iv) 7n = 1.05
Or, 7n/7 = 1.05/7
∴ n = 0.15
(d) (i) a/2 = 8
Or, a/2 X2 = 8 X 2
∴ a = 16
(ii) 15 = d/2
Or, d/2 X2 = 15 X 2
∴ d = 30
(iii) n/3 = -2
Or, n/3 X3 = – 2 X 3
∴ n = – 6
(iv) 1.8m = 36
Or, 1.8m/1.8 = 36/1.8
∴ m = 20
(4) (a) x/3 = 4
Or, x/3 X3 = 4 X 3
∴ x = 12
(b) – 10 = y/5
Or, y/5 X5 = – 10 X 5
∴ y = – 50
(c) 2/3 a = – 8
Or, 2/3 a X 3/2 = – 8 X 3/2
Or, a = – 12
(d) 21 = 3C
Or, 3c/3 = 21/3
∴ c = 7
(e) 18 + k = 7
Or, 18 + k – 18 = 7 – 18
∴ k = – 11
(f) P – 5 1/4 = 3 1/3
Or, P – 5 1/4 + 5 1/4 = 3 1/3 + 5 1/4
Or, P = 10/3 + 21/4
Or, P = 40+63/12
Or, P = 103/12
∴ P = 8.583
(g) 2.3 = n – 1.7
Or, n – 1.7+1.7 = 2.3+1.7
∴ n = 4
(h) x + 10 = 12.5
Or, x + 10 – 10 = 12.5 – 10
∴ x = 2.5