There were two containers of oil. there was twice as much oil in the second container as in the first one. after using 13 liters of oil from the first container and 7 liters from the second one, the second container still had 3 times more oil than the first one. how many liters of oil in total were in both containers originally?

Astudent is determining the influence of different types of food on the growth rate of spiders. she feeds one group of spiders two caterpillars twice a week. the other group received similarly-sized beetles twice a week. she records the amount of time required for individuals to reach sexual maturity. her hypothesis is that the spiders feeding on caterpillars will have a faster growth rate because caterpillars have a higher protein content compared to beetles. in this experiment, what is the dependent variable? spiders assigned to different feeding groups. time required to reach sexual maturity number of prey items fed twice a week. growth rates of each group.