Respuesta :
Answer:
12 of the 5 cents stamps,
20 of the 6 cents stamps
15 of the 8 cents stamps
10 of the 30 cents stamps.
Step-by-step explanation:
Let's name:
x = number of 5 cent stamps,
w = number of 6 cent stamps,
y = number of 8 cent stamps,
z = number of 30 cent stamps,
Create the following system of equations based on the info provided:
z + 5 = y
w = 2 * z
x = 12
600 = 5 (12) + 6 w + 8 y + 30 z
replace everything in terms of "z":
600 = 60 + 6 (2 * z) + 8 (z + 5) + 30 z
540 = 12 z + 8 z + 40 + 30 z
500 = 50 z
z = 10
and now we can find the rest:
y = 5 + 10 = 15
w = 2 * 10 = 20
Therefore there are:
12 of the 5 cents stamps,
20 of the 6 cents stamps
15 of the 8 cents stamps
10 of the 30 cents stamps.