Why wont the opposite of a postive number never be a postitive number

A patio was to be laid in a design with one tile in the first row, two tiles in the second row, three tiles in the third row, and so on. Mr. Tong had 60 tiles to use. How many tiles should be placed in the bottom row to use the most tiles?

Solve for x. - 18<9x

Which graph shows the solution set for - 5/2 x - 3

A wheel made 513 revolutions at 68 3/7 per minute. How minutes did it rotate?

What is the product 2• (-7) A.-9 B.-2 C.-14 D. 14

Jeffrey spent 2/3 hour on his homework how many minutes did he spend on home work

Sum of 7x times 7 + 3x+1 and - 4x times 4-x+3

2. If y (x-1) = z then x=

John (whose line of sight is g ft above horizontal) is trying to estimate the height of a tall oak tree. He first measures the angle of elevation from where he is standing as 30 degrees.

Question: Carbon-11 has a half-life of about 20 minutes. If we start with 200 grams, how much will be left after 3 hours? A. 25 grams B. 2.5 grams C. 0.39 grams D. 0.039 grams