Nthe metric system, how many microseconds are needed to make one second?

Issof claims that the scale factor is 1/2. which statement about his claim is correct

Tim's phone service charges $26.39 plus an additional $0.21 for each text message sent per month. if tim's phone bill was $31.64, which equation could be used to find how many text messages, x, tim sent last month?

What is the slope of the line that contains the points (-2,1) and (0,-3)