#color(blue)("Three very important facts")#
#color(red)("1: ")#The structure of a fraction is such that you have:
#" "("count")/("size indicator of what you are counting")->("numerator")/("denominator")#
#color(red)("2: ")#You can not #ul("directly")# add or subtract the counts unless the
#" "#size indicators are the same.
#color(red)("3: ")#Multiply by 1 and you do not change the value. However, 1
#" "#comes in many forms. So you can change the way something
#" "# looks without changing its true value.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
#color(blue)("Answering the question")#
#color(green)(-[color(white)(2/2)8/10color(red)(xx1)" "]+[color(white)(2/2)17/20" "]-[color(white)(2/2)2/5color(red)(xx1)" "])#
#color(green)(-[color(white)(2/2)8/10color(red)(xx2/2)" "]+[color(white)(2/2)17/20" "]-[color(white)(2/2)2/5color(red)(xx4/4)" "])#
#" "-[color(white)(2/2)16/20" "]" "+[color(white)(2/2)17/20" "]-" "[color(white)(2/2)8/20" "]#
Now that all the denominators are the same we can directly compare the counts.
#(-16+17-8)/(20)" "=-7/20#
