Simplify the ratio of 7 / 20 to 5 / 7

Simplify the ratio of 7 / 20 to 5 / 7

The result is 1 / 4. If the numerator of 7 / 20 and the denominator of 5 / 7 are deleted, 5 / 20 will be obtained. If the numerator and denominator are deleted at the same time, it will be 1 / 4