If a  : b = 2 : 3, b : c = 4 : 5, c : d = 6 : 7, then a : d = ?

To solve this problem, we need to find the ratio of a to d. We can do this by multiplying the ratios together.

Step 1: Multiply the first two ratios together to get the ratio of a to c.

a : b = 2 : 3 and b : c = 4 : 5.

Since b is the common term, we can multiply these ratios together.

(a/b) * (b/c) = (a/c)

(2/3) * (4/5) = 8/15

So, a : c = 8 : 15

Step 2: Multiply this ratio by the third ratio to get the ratio of a to d.

a : c = 8 : 15 and c : d = 6 : 7.

Since c is the common term, we can multiply these ratios together.

(a/c) * (c/d) = (a/d)

(8/15) * (6/7) = 48/105

So, a : d = 48 : 105.