which expression results in a sum or difference of three and ten forty seconds

Number 1,
Since we know the outcome to the equation has to [tex]3\frac{10}{43}[/tex], we can solve each problem regularly to get the answer
_________________
[tex]\huge\blue{\mid{\fbox{\tt{NUMBER\:ONE}}\mid}}[/tex]
[tex]6\frac{5}{7}-6\frac{2}{6}\\\\3\frac{8}{21}[/tex]
_________________
[tex]\huge\blue{\mid{\fbox{\tt{NUMBER\:TWO}}\mid}}[/tex]
We simply can eliminate this option due to it being addition, when one of the numbers is already bigger than what we want,
_________________
[tex]\huge\blue{\mid{\fbox{\tt{NUMBER\:THREE}}\mid}}[/tex]
[tex]8\ \frac{8}{14}-5\ \frac{1}{3}\\\\3 \frac{5}{21}[/tex]
This equation also equals to [tex]3 \frac{10}{42}[/tex], so we found our answer!