Answer:
4.00
Step-by-step explanation:
Let x = the number of 15-cent stamps and y = the number of 20-cent stamps.
x($0.15)+y($0.20) = $4.00 and...
x = 3y-8 "The number of 15-cent stamps (x) is eight less than three times the number of 20-cent stamps (3y-8)" Substitute the x here into the first equation and solve for y.
(3y-8)(0.15)+y(0.20) = $4.00 Simplify.
(0.45)y-1.20+(0.20)y = 4.00
