2/7 + 5/7 =

quien sabe el resultado pls

On a string instrument, the length of a string varies inversely as the frequency of its vibrations. an 11-inch string has a frequency of 400 cylces per second. find the frequency of a 10-icnch string.

45% of the trees in a park are apple trees. there are 27 apple trees in the park. how many trees are in the park in all?

Worth 30 points! in this diagram, both polygons are regular. what is the value, in degrees, of the sum of the measures of angles abc and abd?