Let's calculate the total cost for the goody bags:
1. Slinkys: $0.25 x 4 = $1.00
2. Silly Putty: $1.34 x 4 = $5.36
3. Toy Cars: $2.15 x 4 = $8.60
Now, add up the costs: $1.00 + $5.36 + $8.60 = $14.96
Therefore, the goody bags will cost $14.96 for his 4 friends.
Workout:
\[0.25 \times 4 + 1.34 \times 4 + 2.15 \times 4 = 1.00 + 5.36 + 8.60 = 14.96\]