Does 1:5, 5:15 form a proportion

Question

Do these two ratios 1:5, 5:15 form a proportion

Answer 1

1:5 can be written 3:15. (5:15 is the same as 1:3 or the fraction 1/3.)

So the ratio of 1:5 to 5:15 is 3:15 to 5:15 or 3:5.

The ratio can be expressed as a fraction or proportion 3/5. 1/5 is 3/5 of 1/3.