Answer:
dvd cost $12 each
book cost $1 each
Step-by-step explanation:
3d + 4b = 40
d + 6b = 18
substitution method:
d = 18-6b
3(18-6b) + 4b = 40
54 - 18b + 4b = 40
-14b = -14
b = $1
d + 6 = 18
d = $12
1 7/15
4/5 = 12/15
2/3 = 10/15
12/15 + 10/15 = 22/15 or 1 7/15
RS + ST = 8
(RS + ST)×RS = (4 + 2)×4
8 × RS = (4 + 2) × 4 = 6 × 4 = 24
RS = 24/8 = 3
3 + ST = 8
ST = 5
12
·×=
=12