Question 59758
LET N= THE NUMBER OF NUICLES & D = THE NUMBER OF DIMES THEN
YOU NEED TWO FORMULAS AS YOU HAVE TWO UNKNOWNS.
N+D=20 OR N=20-D
SEEING AS A NICKEL IS WORTH 5 CENTS AND THE DIMES ARE WORTH 10 CENTS THEN
5N+10D=160 
SUBSTITUTING (20-D)FOR N IN EQUATION #2 WE GET
5(20-D)+10D=160
100-5D+10D=160
5D=60
D=60/5
D=12 NUMBER OF DIMES THEN 
N+12=20
N=20-12
N=8 NUMBER OF NICKELS
PROOF
5*8+12*10=160
40+120=160
160=160