If x:y=3:4 then (7x+3y): (7x-3y) is equal to:

Sure, let's solve this step by step:

Step 1: We know that x:y = 3:4. This means that x/y = 3/4.

Step 2: We need to find the ratio (7x+3y) : (7x-3y).

Step 3: Substitute x/y = 3/4 into the equation.

Step 4: The equation becomes (73 + 34) : (73 - 34) = (21+12) : (21-12) = 33:9.

Step 5: Simplify the ratio 33:9 to its simplest form by dividing both numbers by their greatest common divisor, which is 3.

So, the ratio (7x+3y) : (7x-3y) simplifies to 11:3.