Question 161983
x=# of 3cent stamps

3x-1=# of 8 cent stamps

(3x-1)-6=# of 15cent stamps

Total value is $2.47

.03x+.08(3x-1)+.15(3x-7)=2.47


Use the distributive property

.03x+.24x-.08+.45x-1.05=2.47

Combine like terms and simplify

(.03+.24+.45)x+(-.08-1.05)=2.47


(0.72)x-1.13=2.47

add 1.13 to both sides

.72x=3.6

divide both sides by .72

x=5

# of 3 cent stamps is 5

# of 8 cent stamps =3(5)-1=14

# of 15 cent stamps is 14-6=8

Let's double check our answer

.03(5)+.08(14)+.15(8)=.15+1.12+1.2=2.47