Two numbers x and y are in the ratio 5 : 7 and their sum is Then x is

The correct answer is (b).

Two numbers x and y are in the ratio 5 : 7. This means that x is 5 parts and y is 7 parts. We can write this as a proportion:

$$x:y = 5:7$$

We also know that the sum of x and y is 18. We can write this as an equation:

$$x+y = 18$$

We can solve this equation for x by multiplying both sides by 7:

$$7x+7y = 126$$

Subtracting 7y from both sides, we get:

$$7x = 126-7y$$

Dividing both sides by 7, we get:

$$x = \frac{126}{7} – y$$

Substituting in the value of y from the proportion, we get:

$$x = \frac{126}{7} – 7$$

Simplifying, we get:

$$x = 5$$

Therefore, the correct answer is (b).