Santiago found 5/6 of a leftover pizza in the refrigerator and ate 3/6 of it. How much leftover pizza was there then?

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Answer 1 · 2017-10-17T12:22:57

See a solution process below:

Let's call the final amount of left over pizza: #p#

We can then write and solve for #p#:

#p = 5/6 - (3/6 xx 5/6)#

#p = 5/6 - (3 xx 5)/(6 xx 6)#

#p = 5/6 - 15/36#

#p = (6/6 xx 5/6) - 15/36#

#p = (6 xx 5)/(6 xx 6) - 15/36#

#p = 30/36 - 15/36#

#p = (30 - 15)/36#

#p = 15/36#

#p = (3 xx 5)/(3 xx 12)#

#p = (color(red)(cancel(color(black)(3))) xx 5)/(color(red)(cancel(color(black)(3))) xx 12)#

#p = 5/12#

There was #5/12# of the pizza left.

Another approach is to recognize:

#3/6 = 3/(3 xx 2) = color(red)(3)/(color(red)(3) xx 2) = 1/2#

If Santiago ate half of the left over pizza, then half of the left over pizza would remain.

#1/2 xx 5/6 = (1 xx 5)/(2 xx 6) = 5/12#