Answer:
He sold 10 hangers and 10 neclesses
Explanation:
Given data
Let the number of door hanger be x
and the number of neckless be y
so
x+y= 20---------1
also,
2.25x+3.75y= 60---------2
Solve 1 and 2 together
From 1
x= 20-y
put this in place of x in 2
2.25(20-y)+3.75y= 60
45-2.25y+3.75y= 60
1.5y= 60-45
1.5y= 15
y= 15/1.5
y= 10
Put y= 10 in 1
x+10= 20
x= 20-10
x= 10