How do I simplify this in exponential expression ​

How do i put 3(x+7) in distributive property

Aplane intersects a pris paralel to the base of the prism. the cross section is a polygon wth eight sides. how many sides does the base of the prism have? a. 10 b. 8 c. 7 d. 9

George writes the mixed number as sum and uses the distributive property 1/2.-2/5=1/2-2+2/5=1/2