10 years, because In 5 years after 2008, 2013 you get new math books 5 more years you get another set of math books-2018, but 2008 plus 10 years you get science books which is also 2018 which is also when you get another set of math books. So the next year you get math books and science books shipped the same year is 2018. 2018-2008=10 so 10 years pass
Answer:
third one is not true means wrong
Cost of company A=monthlyfee+text=20+0.03t where t=number of texts
A=20+0.03t
company b is monthlyfee+texts=5+0.07t
B=5+0.07t
1.
c=20+0.03t
c=5+0.07t
using c for cost is confusing because we can't tell which is for which company
2.
equal, means the costs are equal so
20+0.03t=5+0.07t
minus 5 from both sides
15+0.03t=0.07t
minus 0.03t from both sides
15=0.04t
divide both sides by 0.04
375=t
the answer is 375 texts
