Chapter 7: Algebra

Solution:-

(A) p + q

From the question it is given that,

Kanta has p pencils in her box

She puts q more pencils in the box

The total number of pencils with her are = p + q

Solution:-

(A) 4

Consider the given equation 4x = 16

Then, value of x is,

x = 16/4 … [divide both numerator and denominator by 4]

x = 4

Solution:-

(D) x + 13 = 27

Let us assume the number be ‘x’,

Then, adding 13 to the number = x + 13

Therefore, x + 13 = 27

In question 24 to 40, fill in the blanks to make the statements true:

Solution:-

The distance (in km) travelled in h hours at a constant speed of 40km per hour is 40h.

From the question,

Time taken to travel a distance = h hours

Travel at a speed of 40 km/h

So, total distance travelled = 40 × h

= 40h

Solution:-

p kg of potatoes are bought for Rs 70. Cost of 1kg of potatoes (in Rs) is 70/p.

Given, p kg of potatoes are bought for ₹ 70

Then, cost of 1 kg of potato = 70/p

Solution:-

An auto rickshaw charges Rs 10 for the first kilometre then Rs 8 for each such subsequent kilometre. The total charge (in Rs) for d kilometres is 2 + 8d.

From the question it is given that,

An auto rickshaw charges ₹ 10 for the first kilometre

Then ₹ 8 for each such subsequent kilometre.

So, the total charge (in Rs) for d kilometres is = 10 + (d – 1)8

= 10 + 8d – 8

= 2 + 8d

Solution:-

If 7x + 4 = 25, then the value of x is 3.

Consider the equation, 7x + 4 = 25

Transposing 4 from left hand side to right hand side it becomes -4,

7x = 25 – 4

7x = 21

x = 21/7

x = 3

Solution:-

The solution of the equation 3x + 7 = –20 is -9.

Consider the equation, 3x + 7 = –20

Transposing 7 from left hand side to right hand side it becomes -7,

3x = – 20 – 7

3x = – 27

x = -27/3

x = – 9

Solution:-

‘x exceeds y by 7’ can be expressed as x – y = 7.

Solution:-

‘8 more than three times the number x’ can be written as 3x + 8.

As per the condition given in the question, three times the number x = 3x

So, 8 more than three times the number x = 3x + 8