Exercise 3.8.76. [S][Section 3.4] [Goal 3.2] [Goal 3.4] [Goal 3.5][Goal 3.5][Goal 3.6] Bat- teries are cheaper. In April 2019 Politico reported that The cost of lithium-ion batteries has plunged 85 percent in a decade, and 30 percent in just the past year, [R145] What was the percent drop in battery cost for the first nine years of the decade reported on