Question

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Answer 1

Find the present age of A and B if 4 years back ,their age ratio was 2:3 and after 4 years the age ratio will be 5:7

Definition:

Ratio is a relationship between two quantities , normally expressed as the quotient of one divided by the other.

Step-by-step explanation:

Let "x" be the present age of A and "y" be the present age of B.

As we know that their age ratio before 4 years was 2:3,therefore

$\frac{x-4}{y-4}=\frac{2}{3} \\3(x-4)=2(y-4)\\3x-12=2y-8\\3x-2y=-8+12\\3x-2y=4$(1)

And we also know that their gar ratio after 4 years was 5:7,therefore

$\frac{x+4}{y+4}=\frac{5}{7}\\7(x+4)=5(y+4)\\7x+28=5y+20\\7x-5y=20-28\\7x-5y=-8$(2)

Multiply (1) by 5 and (2) by 2

$15x-10y=20\\14x-10y=-16$

Subtract the above two equations

$15x-10y=20\\(-) 14x-10y=-16$

As these is the subtraction so sign of the second equation changes,therefore

$15x-10y=20\\-14x+10y=16\\-------------\\x=36$

Substitute the value of x in any one of the equation

$3x-2y=4\\3(36)-2y=4\\108-4=2y\\104=2y\\y=52$

Therefore,the present age of A is 36 and B is 52

Answer 2

Answer:

Step-by-step explanation: