12. Write the sum 54 + 63 as the product of a number and relatively prime addends: 54 + 63

9 (7 + ?)

Is the orthocenter of a triangle on the inside ?

With these: 18/36 = 1/? missing number change 1 5/8 to improper fraction. change 19/5 to a mixed number.

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.