Well if you buy only 1 of each, it would cost you 7.85 in total. if you subtract that from 20, it equals 12.15.
you can also make it a linear equation if you want more or less than 1 fruit and or sandwich
s=sandwich
f=fruit
5.7f+2.15f=20
I'm sorry but I do not understand your question. It is not specified what you are looking for.
I prefer decimals with common denominators so I'm going to go ahead and convert them.
-1.25+.50 = -.75
-.75 is -3/4 aka "c" or the third option.
44% Is the answer, Think Of 50-50