`13/7 xx 12/13 + 13/7 xx 27/13`
`= 13/7 xx (12/13 + 27/13)`
`= 13/7 xx 3`
`= 39/7`
\(\dfrac{13}{7}\times\dfrac{12}{13}+\dfrac{13}{7}\times\dfrac{27}{13}\)
\(=\dfrac{13}{7}\times\left(\dfrac{12}{13}+\dfrac{27}{13}\right)\)
\(=\dfrac{13}{7}\times\dfrac{39}{13}\)
\(=\dfrac{13}{7}\times3\)
\(=\dfrac{39}{7}\)