Question 63714
N+D+Q=42 GIVEN
700=5N+10D+25Q GIVEN
D=2N
Q=3N NOW WE SUBSTITUTE THESE BVALUES INTO EITHER EQUATION & WE GET
N+2N+3N=42
6N=42
N=42/6
N=7 NUMBER OF NICKELS
D=2*7
D=14 NUMBER OF DIMES
Q=3*7
Q=21 NUMBER OF QUARTERS 
PROOF
700=5*7+10*14+25*21
700=35+140+525
700=700