Question

1/4 pizza for 5 dollars, how much can you purchase for 8 dollars

Answer 1

ONE 
to buy more than one you would need at least 10 dollars 

Answer 2

You set up a proportion

0.25 pizza/ 5 dollars = x pizza/ 8 dollars
0.25/5 = x/8
Now solve for x
Multiply both sides by 8
0.25(8)/5 = x
4/5 = x

You can buy 4/5 of a pizza