The sum of two numbers is 30 the difference of the two numbers is 4 what is the lesser number?

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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.

Perform the indicated operation and write the answer in the form a + bi. (-5 + 2) + (3 - 6i)