300 total
1 2 and 5
Number of 2 coins is 3times the number of 5 coins total number of coins is 160
Okay lets begin
Let x = number of 1 coins
Y= 2 coin
Z= 5coin
Number of 2 coin is 3times the number of 5coins means
y=3z
Total number of coins is 160 means
x+y+z=160
Then total amount is 300 means
X+2y+5z=300
Solve simultaneously
substitute
Y=3z to x+y+z=160 and x+2y+5z=300
so, x+3z+z=160 and x+2(3z)+5z=300
Simplify
x+4z=160 and x+11z=300
Solve simultaneously
x=160-4z
160-4z+11z=300
7z=300-160
7z=140
z=20
y=3z so y=60
and x+y+z=160
so x=160-y-z
x=160-20-60
x=80
This is just a simple solution if you try to understand it