Page 155 - ICSE Math 7

EXERCISE 13.4

1. Find two numbers whose sum is 55 and difference is 7.

2. Half of a number exceeds one-fourth of it by 9. Find the number.

3. The sum of three consecutive odd natural numbers is 105. Find the largest of the three numbers.
4. The age of a father is thrice his son’s age. If half of father’s age exceeds half of son’s age by
22 years. Find their present ages.
5. Divide 80 mangoes between X and Y so that X gets 14 mangoes more than Y.

6. The perimeter of a rectangle is 126 m. If its length is 5 m more than its breadth, find the sides of
the rectangle.
7. The price of apples is twice the price of grapes. Sia buys 2.5 kg grapes and 1.5 kg apples for
` 330. Find the price of the apples and grapes per kilogram.

1 2
8. Rohan reads of a book on Friday, of it on Saturday and the remaining 60 pages on Sunday.
6 3
Find the total number of pages in the book.

9. The length a pole below the earth is two-fifth of its length above the earth. If the length of the
pole is 49 m, find the length of the pole below the earth.

10. How many kilograms of rice at ` 50 per kilogram should be mixed with 10 kilograms of rice at
` 80 per kilogram to get a mixture of ` 70 per kilogram?

AT A GLANCE

¾ An equation is a mathematical statement which shows the equality of two expressions.
¾ A linear equation is one in which the highest power of the variable(s) is one.

¾ The value of the variable which satisfies the equation is called the solution or root of the equation.
¾ To maintain balance or equality in an equation, we can
(a) add same number on both sides. (b) subtract same number on both sides.
(c) multiply both sides by the same number. (d) divide both sides by same non-zero number.

¾ Transposing means moving a term from one side to the other. Whenever a constant or variable
term is moved from one side to the other, its sign changes. Transposing a number has the same
effect as adding or subtracting a constant on both sides.

¾ In systematic method of solving an equation, we perform identical mathematical operations on
both sides of the equation to obtain the solution of the variable.
¾ An equation remains same if its LHS and RHS are interchanged.

MENTAL MATHS

1. Choose the correct answer.
(a) Which of the following is the solution of 3x + 7 = 13 ?

(i) 1 (ii) –1 (iii) 2 (iv) 3

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