Perform the indicated operation. Express your answer in simplest form.
-$$\frac { 20 } { 21 } - \frac { 12 } { 19 }$$
A) $\frac { 128 } { 21 }$
B) $\frac { 128 } { 399 }$
C) $\frac { 8 } { 399 }$
D) $\frac { 399 } { 128 }$

Question

Quizplus · Accepted Answer

To subtract fractions with different denominators, find a common denominator, which is the least common multiple (LCM) of the denominators. Here, LCM of 21 and 19 is 399. Convert each fraction to have this common denominator and then subtract: $\frac{20}{21} \times \frac{19}{19} - \frac{12}{19} \times \frac{21}{21} = \frac{380}{399} - \frac{252}{399} = \frac{128}{399}$.

Perform the Indicated Operation 2021−1219\frac { 20 } { 21 } - \frac { 12 } { 19 }2120​−1912​

Perform the Indicated Operation $\frac { 20 } { 21 } - \frac { 12 } { 19 }$