Answer :
you must make there be a common denominator(lower number) so 9/10*3(otherwise known as 3/3)=27/30 1/3*10(otherwise known as 10/10=10/30 now we do the math 27/30-10/30=17/30 when you add or subtract fractions you always find a common denominator then only add or subtract the numerator (top number)
[tex] \frac{9}{10}- \frac{1}{3}= \\
\\ \frac{9*3}{10*3}= \frac{27}{30} \\
\\ \frac{1*10}{3*10}= \frac{10}{30} \\
\\ \frac{27}{30}- \frac{10}{30}= \frac{17}{30} \\
\\ Answer:\boxed{ \frac{10}{30}} \\ [/tex]
