Question

A certain type of mixture is prepared by mixing brand a at rs.9 a kg. With brand b at rs.4 a kg. If the mixture is worth rs.7 a kg., how many kgs. Of brand a are needed to make 40kgs. Of the mixture?

Answer 1

Ratio can be your KEY

Answer 2

Answer:

24

Step-by-step explanation:

A + B = 40.

And at Rs 7 a kg for 40 kg, you want a total of Rs.280.

So the second equation is 9A + 4B = 280

From the first equation: B = 40 - A

and sub into the second equation:

9A + 4(40-A) = 280

9A + 160 - 4A = 280

5A = 120

A = 24.

And you should check: B should equal 40-24 = 16. Check with the final equation: 9*24 + 4*16 = 216 + 64 = 280. So it works.

Your answer, of course, is A = 24