Adding fractions with unlike denominators 1/3 + - 2/7

1/21

Step-by-step explanation:

Changing operations to eliminate negative numerators the equation becomes

=1/3−2/7

With unlike denominators find the Least Common Denominator (LCD)

LCD = 21

Multiplying numerators and denominators to get the LCD in all fraction denominators

=1×7/3×7  −2×3 /7×3

Then rewriting the equation with the equivalent fractions

=7/21−6/21

With like denominators we can operate on just the numerators

=7−6/21

=1/21