Which algebraic expression represents the sum of a number and 9?
O 7-9
On9
Ogn
10)

Dylan and dusty plan to take weekly surfing lessons together. if the 2-hour lessons are $20 per person and they plan to spend $100 each on new surfboards, what is the maximum number of lessons the two can take if the total amount spent for lessons and surfboards is at most $480?

Write two subtraction equations that are equivalent to 5 + 12 = 17.

The standard deviation for a set of data is 5.5. the mean is 265. what is the margin of error?