Subtract the expressions given below: (6a + 9b - 18) - (9a - 6b + 14) Class 7

Subtract the expressions given below: (6a + 9b - 18) - (9a - 6b + 14) Class 7

Question 1.

Subtract the expressions given below:

(a) (6a + 9b - 18) - (9a - 6b + 14)

Solution:

(6a + 9b - 18) - (9a - 6b + 14)

= 6a + 9b - 18 - 9a + 6b - 14

= 6a - 9a + 9b + 6b - 18 - 14

= - 3a + 15b - 32

(b) (7y - 10 + 3x) - (-15x + 13 - 9y)

Solution:

(7y - 10 + 3x) - (-15x + 13 - 9y)

= 7y - 10 + 3x + 15x - 13 + 9y

= 7y + 9y + 3x + 15x - 10 - 13

= 16y + 18x - 23

(c) (11 - 10g + 3h) - (17g + 9 - 7h)

Solution:

(11 - 10g + 3h) - (17g + 9 - 7h)

= 11 - 10g + 3h - 17g + 9 + 7h

= 11 - 9 - 10g - 17g + 3h + 7h

= 2 - 27g + 10h

(d) 6a - (9b + 18) - (9a - 6b + 14)

Solution:

6a - (9b + 18) - (9a - 6b + 14)

= 6a - 9b - 18 - 9a + 6b - 14

= 6a - 9a - 9b + 6b - 18 - 14

= - 3a - 3b - 32

(e) -3y + 8 - 3x - (10x + 2 + 10y)

Solution:

-3y + 8 - 3x - (10x + 2 + 10y)

= -3y + 8 - 3x - 10x - 2 - 10y

= -3y - 10y - 3x - 10x + 8 - 2

= -13y - 13x + 6

(f) 7h - 8g + 20 - (8g + 4h -10)

Solution:

7h - 8g + 20 - (8g + 4h - 10)

= 7h - 8g + 20 - 8g - 4h + 10

= 7h - 4g - 8g - 8g + 20 + 10

= 3h - 16g + 30

Question 2.

Describe situations corresponding to the following algebraic expressions: Class 7

(a) 8x + 3y

(b) 15x - 2x

Solution:

(a) Cost of 8 pencils and 3 pens.

(b) Difference of the cost of 15 and 2 articles.