Question

john has us and foreign stamps in his album. the ratio of the numer of us stamps to foreign stamps is 5:2. after paul gives him 12 foreign stamps the ratio becomes 2:1. find the number of us stamps he has.

Answer 1

Answer:

The number of U.S stamp he has is 120.

Step-by-step explanation:

John has us and foreign stamps in his album. the ratio of the number of U.S stamps to foreign stamps is 5:2.

After Paul gives him 12 foreign stamps the ratio becomes 2:1.

Now, to find the number of U.S stamps.

Let the U.S stamps be $x.$

And the foreign stamps be $y.$

Now, to solve by using cross multiplication method:

So, the ratio is:

$\frac{x}{y} =\frac{5}{2}$

By cross multiplying we get:

$2x=5y$

Dividing both sides by 2 we get:

$x=\frac{5y}{2}$......(1)

Now, after Paul gives him 12 foreign stamps the ratio becomes:

$\frac{x}{12+y} =\frac{2}{1}$

By cross multiplying we get:

$x=24+2y$

Putting the value of $x$ as we get in above equation (1):

$\frac{5y}{2} =24+2y$

Multiplying both sides by 2 we get:

$5y=48+4y$

Subtracting both sides by 4y we get:

$y=48.$

The number of foreign stamps = 48.

Now, to get the number of U.S stamps by putting the value of $y$ in equation (1):

$x=\frac{5\times 48}{2}$

$x=\frac{240}{2}$

$x=120.$

Therefore, the number of U.S stamp he has is 120.