Step-3

Title: Ratios

Grade: 8-a Lesson: S2-L4

Explanation: Let us verify the answer here with the steps.

Description:

Step Type Explanation Answer

1

Problem

The monthly incomes of two persons are in the ratio of 5:6, and their monthly expenditures are in the ratio of 7:9. If each saves $54 per month, find the monthly income of the 2nd person.

2

Hint

Operator used : Ratio

:

3

Step

According to the problem

The ratio of incomes of two persons = 5:6

Expenditure ratio = 7:9

4

Step

Income of first person

\$5x\$

5

Step

Income of second person

\$6x\$

6

Step

We know that Expenditure

Income - Savings

7

Step

Expenditure of first person

\$5x - 54\$

8

Step

Expenditure of second person

\$6x - 54\$

9

Step

So, we have

\$(5x - 54) : (6x - 54) = 7:9\$

10

Step

Use cross product rule,

\$9(5x - 54) = 7(6x - 54)\$

⇒ \$45x - 486 = 42x - 378\$

⇒ \$\cancel3^1x = \cancel108^36\$

11

=

\$x = 36\$

12

Step

Then the income of the 2nd person is 6x = 6(36)

108


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