Company B had three types of vehicles. Vehicle 1 had a cost of $35,000, salvage value of $8,000, and useful life of 6 years. Vehicle 2 had a cost of $58,000, salvage value of $3,000 and useful life of 10 years. Vehicle 3 had a cost of $19,500, salvage value of $1,500, and useful life of 4 years. What is the composite life? 6.7 years 6.9 years 7.7 years 7.8 years