Question

If x : y = 3 : 4, then find the value of ( 3x + 4y) : (4x + 7y)

Answer 1

Hope its helpful............

Answer 2

Answer:

5 : 8

Step-by-step explanation:

Find x in term of y:

x : y = 3 : 4

⇒ x/y = 3/4

⇒ 4x = 3y

⇒ x = 3/4 y

Find 3x + 4y in term of y:

3x + 4y = 3( 3/4 y) + 4y

3x + 4y =9/4 y + 4y

3x + 4y =25/4 y

Find 4x + 7y in term of y:

4x + 7y = 4(3/4 y) + 7y

4x + 7y = 3y + 7y

4x + 7y = 10 y

Find the ratio:

( 3x + 4y) : (4x + 7y) = 25/4 y : 10 y

Divide both sides by y:

( 3x + 4y) : (4x + 7y) = 25/4  : 10

Multiply both sides by 4:

( 3x + 4y) : (4x + 7y) = 25 : 40

Divide both sides by 5:

( 3x + 4y) : (4x + 7y) = 5 : 8

Answer: 5 : 8