You'd fine the unit rate, in the context of the problem it would be how many minutes it takes for 1 pizza to cook
20/4= 5 minutes for 1 pizza
we are finding how long it would take to cook 10
5 times 10= 50, so 50 minutes
It would be 10 times greater im pretty sure.
C^2=a^2+b^2
6^2=5^2+b^2
36=25+b^2
b^2=36-25
b^2=11
b= √11
b=3.3166
If you need to round it to the tenth place,
b~3.3
to hundreds place,
b~3.32
Good luck