John is twice as old as Mary. The sum of their ages is 21. How old is Mary? Let J = John's age and M = Mary's age. Select the system equations that represent the problem.

Write a fraction equivalent of 1/7

Which expression is equivalent to (4^5/4 4^1/4/4^12) ^1/2

A group of seven students were asked how much tv do you watch a day Here are their response 12, 5, 5, 4, 10, 15, 16 Find the mean number of hours for these students. If necessary, round your answer to the nearest tenth.

Is there an answer. If a girl had - 9 then what's the opposite of that number

Sin (π) + 4cos (π) = x - cos (π/2)

A prom ticket at Smith high school is $120. Tom is going to save money for the ticket by walking his neighbor's dog for $15 per week.

The product of two consecutive pages is 182 find the page number

Surface area of two spheres are in the ratio 36:25 find the ratio of their volumes

Let a = {1, 2, 3, 4, 5} and b = {2, 4}. what is a ∩ b?

Phillipa says that (27 - 9) x 3: 9 + 18 = 42. Is she correct? If not, what is the correct answer? O A. She is correct. B. She is not correct. The correct answer is 2. C. She is not correct. The correct answer is 24. D. She is not correct.