Susan got a prepaid debit card with $20 on it. For her 1st purchase with the card, she bought some bulk ribbon at a 23 cents per yard. If after the purchase there was $16.09 left on card, how many yards of ribbon did Susan buy?

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.