Question

Item 17 There were nn signers of the Declaration of Independence. The oldest was Benjamin Franklin, who was yy years old. 7 is 10% of yy and nn is 80% of yy. How many signers were there?

Answer 1

7 is 10% of yy then we get the equation :
0.1*yy=7 so yy=7/0.1=70.
also, 
nn=0.8*yy.
 so nn=0.8*70=56. 
There were 56 signers then.