#color(blue)("Two very important facts")#
#color(brown)("Fact 1")#
You can not #ul("directly")# add or subtract counts in fractions unless their 'size' indicators are the same.
#("count")/("size indicator")->("numerator")/("denominator")#
'......................................................................................
#color(brown)("Fact 2")#
Multiplying by 1 does not change the intrinsic value of something.
Multiply by 1 in some different form does not change the intrinsic value but #ul("does change the way it looks")#.
'~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
#color(blue)("Answering your question")#
#color(brown)((5/7xx1)-(2/3xx1))color(blue)(" "->" "(5/7xx3/3)-(2/3xx7/7)#
#=(5xx3)/(7xx3) - (2xx7)/(3xx7)#
#=15/21-14/21#
#(15-14)/21 = 1/21#
