A chemist has one solution containing 50% acid and a second one containing 25% acid.

Let x litres and y litres be the amount of acids from 50% and 25% acid solutions respectively. 

As per the question 

50% of x + 25% of y = 40% of 10

⇒ 0.50x + 0.25y = 4 

⇒ 2x + y = 16 ………(i) 

Since, the total volume is 10 liters, so 

x + y = 10 

Subtracting (ii) from (i), we get 

x = 6 

Now, putting x = 6 in (ii), we have 

6 + y = 10 ⇒ y = 4 

Hence, volume of 50% acid solution = 6litres and volume of 25% acid solution = 4litres.

Let x litres and y litres be the amount of acids from 50% and 25% acid solutions respectively. 

As per the question 

50% of x + 25% of y = 40% of 10

⇒ 0.50x + 0.25y = 4 

⇒ 2x + y = 16 ………(i) 

Since, the total volume is 10 liters, so 

x + y = 10 

Subtracting (ii) from (i), we get 

x = 6 

Now, putting x = 6 in (ii), we have 

6 + y = 10 ⇒ y = 4 

Hence, volume of 50% acid solution = 6litres and volume of 25% acid solution = 4litres