Answer: 19/36
Explanation:
First the LCM (Least Common Denominater) must be found, the LCM of 9 and 4 is 36
Since 9 x 4 is 36, the numerator and denominator of 7/9 will be multiplied by 4 making it 28/36
Since 4 x 9 equals 36, the numerator and denominator of 1/4 will be multiplied by 4 making it 9/36
Now that they have common denominators the numerators can be subtracted from each other as well as the denominators
28/36 - 9/36 = 19/36
19/36 cannot be simplified therefore 7/9 - 1/4 = 19/36