Activity › Discussion › Math › Ratio and Proportion (Class 7) › Reply To: Ratio and Proportion (Class 7)

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Let’s assume the two numbers in the ratio 7:12 are 7x and 12x, where x is a common multiplier.
According to the given condition, when 7 is added to the first number and 2 is added to the second number, the new ratio becomes 21:31.
So, after adding 7 to the first number, it becomes 7x + 7, and after adding 2 to the second number, it becomes 12x + 2.
Now, we can set up the equation based on the new ratio:
(7x + 7) / (12x + 2) = 21/31
To eliminate the fractions, after crossmultiplying:
(7x + 7) * 31 = (12x + 2) * 21
217x + 217 = 252x + 42
Subtracting 217x from both sides, we get:
217 = 35x + 42
Subtracting 42 from both sides, we get:
175 = 35x
Dividing both sides by 35, we get:
x = 5
Now, we can find the values of the two numbers:
First number = 7x = 7 * 5 = 35; Second number = 12x = 12 * 5 = 60
Answer: The two numbers are 35 and 60.