Question

what number must be subtracted from each term of the ratio 4:9 to get the value of the ratio as 8:7 ​

Answer 1

Let the number subtracted from each term be x.

According to the question,

$\sf{\frac{4 - x}{9 - x} = \frac{8}{7} } \\ \\ \implies 8(9 - x) = 7(4 - x) \\ \implies72 - 8x = 28 - 7x \\ \implies 72 - 28 = 8x - 7x \\ \implies34 = x \\ \therefore \boxed{ \sf{x = 34}}$

So, the number to be subtracted is 34

Additional information:

• Ratio can be written as a fraction.
• When there is a fraction on both LHS and RHS of the equation, they can be equated using Cross multiplication method as done in this question.