In what ratio a mixture of 30% alcohol strength be mixed with that of 50% alcohol strength so as to get a mixture of 45% alcohol strength?

Question: In what ratio a mixture of 30% alcohol strength be mixed with that of 50% alcohol strength so as to get a mixture of 45% alcohol strength?

Solution:
Let the ratio be 1:x
Then according to the question
⇒ 30 × 1 + 50x = (1+x) 45
⇒ 30 + 50x = 45 + 45x
⇒ 50x - 45x = 45 - 30
⇒ 5x = 15
⇒ x = 3

∴ the ratio is 1 : 3