Lou eats 6/8 of pizza what fraction of the pizza es left over

is the full pizza 

So to solve it, you need to minus the amount that Lou ate from the whole pizza

So it would be  

To reduce to the lowest terms, you would find the greatest common factor for both the numerator(top) and the denominator(bottom) so 2 is a common factor 

2÷2=1  and 8÷2=4

So your answer would be 

  is the fraction of the pizza left over