In order to check if these ratios are equivalent, we just need to simplify them to the simplest fraction.
a.
5:1 is already in the simplest fraction: 5/1 = 5:1
15:3 -> 15/3 = 5/1 = 5:1
The ratios in the simplest form are the same, so the ratios are equivalent.
b.
25:5 -> 25/5 = 5/1 = 5:1
10:2 -> 10/2 = 5/1 = 5:1
Both ratios represent the ratio 5:1, so they are equivalent.
Summarizing, we just need to divide the numerator and denominator (or the first and second number in the ratio) and check if the result is the same.
