Answer:
Quaters - Q=12
Dimes - D=10
Nickels - N= 48
Step-by-step explanation:
First, notice that $6.40 = 640 cents. The corresponding linear equation and a solution is shown below in several steps:
Original equation for amount of Dimes (D):
10*D + 25*(D+2) +5*4*(D+2) = 640
Simplified as following, resulting in the answer for D:
55*D=550
D=10
thus having the amount of Quarters:
Q=12
and correspondingly, amount of Nickels:
N= 48
