### Mathematics Class VII

Integers
Fractions and Decimals
Exponents and Powers
Algebraic Equations
Simple Linear Equations
Lines and Angles
Comparing Quantities
Congruence of Triangles
Rational Numbers
Perimeter and Area
Data Handling
Practical Geometry
Symmetry
Visualising Solid Shapes

# Applications Of Simple Equations To Practical Situations

If we have statements related to a practical situation then first we have to convert it in the form of the equation then solve it to find the solution.

Example: 1

Radha’s Mother’s age is 5 years more than three times Shikha’s age. Find Shikha’s age, if her mother is 44 years old.

Solution:

Let Shikha’s age = y years

Her mother’s age is 3y + 5 which is 44.

Hence, the equation for Shikha’s age is 3y + 5 =44

3y + 5  = 44

3y = 44 – 5 (by transposing 5)

3y = 39

y = 13 (by dividing both sides by 3)

Hence, Shikha’s age = 13 years.

Example: 2

A number consists of two digits. The digit in the tens place is twice the digit in the units place. If 18 be subtracted from the number, the digits are reversed. Find the number.

Solution:

Let the digit at units place = y

So, the digit in the tens place = 2y

So, the number is (2y) y.

As it is given that if 18 is subtracted from the number, the digits are reversed.

So, we have

(2y) y – 18 = y(2y) Solve it

20y + y – 18 = 10y + 2y

21y – 18 = 12y

21y – 18 = 12y

9y = 18 (By dividing both sides by 9)

y = 2

The digit at the units place is y = 2.

And the digit at the tens place is 2y = 4

Hence, the required number is 42.

Scroll to Top