on monday byron spent $8.00 on lunch to purchase two tacos and one burrito. on wednesday he purchased one enchilada, one taco, and one burrito and spent $8.50.on friday it cost byron $10.00 for two enchiladas and two tacos .If t representsthe cost of a taco, b represents the cost of a burrito, and e represents the cost of an enchilada , which system of equations can be used to find the cost of taco , t?

Ariana starts with 100 milligrams of a radioactive substance. the amount of the substance decreases by 20% each week for a number of weeks, w. the expression 100(1−0.2)w finds the amount of radioactive substance remaining after w weeks. which statement about this expression is true? a) it is the difference between the initial amount and the percent decrease. b) it is the difference between the initial amount and the decay factor after w weeks. c) it is the initial amount raised to the decay factor after w weeks. d) it is the product of the initial amount and the decay factor after w weeks.