Larry C. answered • 03/05/18
Tutor
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Computer Science and Mathematics professional
When adding or subtracting fraction, you first need to find the least common denominator (LCD) of the fractions involved. This can be done by factoring each to primes.
9 factors to 3*3 and 3 cannot be factored any further. So, the LCD is 9 and the 1/3 needs to be converted to ninths. This is done by multiplying both the numerator and denominator by 3 (Since 3/3=1, the overall value of the fraction is unchanged). Therefore:
7/9 + 1/3 = 7/9 + (1*3)/(3*3) = 7/9 + 3/9 = (7+3)/9 = 10/9 or 1 1/9
