Page 125 - Start Up Mathematics_7

10. Smita’s mother is 34 years old. Two years from now her mother’s age will be 4 times Smita’s
present age. What is Smita’s present age?

11. People of Vrindavan planted a total of 102 trees along the village road. Some of the trees
were fruit-bearing trees. The number of non-fruit-bearing trees was two more than thrice the
number of fruit-bearing trees. What was the number of fruit-bearing trees planted?
Thinking Skills

1. Soumya works in an electronics showroom which sells TV sets. Her base salary is ` 10,000
per month. Soumya also gets an incentive of ` 240 on every TV set she sells. Find the number
of TV sets she should sell in order to earn ` 14,320 next month.
2. Surbhi has borrowed 3 books from the library. The fine for not returning the books in time is
` 5 per day. She remembers the librarian telling her that the Mathematics book was issued to
her about a week earlier than the 2 Science fiction books. If the total fine paid by Surbhi on
all 3 books is ` 125, how long was each book overdue?
3. A mouse is 20 m away from its burrow and can run at 3 m per second. A cat spots the mouse
and starts running towards it at 6 m per second.
(a) How long will it take the mouse to reach its burrow?
(b) If the cat is x metres away from the mouse as shown in the figure, write an expression
which tells how long it will take the cat to reach the burrow.
(c) If the cat pounces upon the mouse when it is about to enter its burrow, find the value
of x.
(d) Interpret your result.

x m 20 m

Values and Life Skills

A typist is engaged in an office on contractual basis for 30 days. In the terms and conditions of
his appointment, it is mentioned that he will get ` 120 per day and if he is absent, an amount
of ` 20 per day will be deducted from his salary. On completion of his contract, he receives
` 2,760 only. For how many days was he present in the office?
What are the factors which affect the performance of a person in the office?

Some NCERT Textbook Questions

1. Check whether the value given in the brackets is a solution to the given equation or not:

(a) n + 5 = 19(n = 1) (b) 7n + 5 = 19(n = –2) (c) 7n + 5 = 19(n = 2)
(d) 4p – 3 = 13(p = 1) (e) 4p – 3 = 13(p = –4) (f) 4p – 3 = 13(p = 0)
2. Solve the following equations by trial and error method:

(i) 5p + 2 = 17 (ii) 3m – 14 = 4

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