Question 27859
Let the satonary be x
Let the envelopes by y
12x+8y=41 --> solve for y
8y=41-12x
y=5.125-1.5x (subsititon)


18x+16y=68.50
Subsitute


18x+16(5.125-1.5x)=68.50
18x+82-24x=68.5
-6x=-13.5
x=2.25


y=5.125-1.5(2.25)
y=1.75


Hence, one box of envelop costs about $1.75.
Paul.