Two numbers have a sum of 1,212 and a difference of 518. which system of equations could we use to solve this problem?

Tim's phone service charges $23.06 plus an additional $0.22 for each text message sent per month. if tim's phone bill was $28.56, which equation could be used to find how many text messages, x, tim sent last month?

Look at arnold's attempt to solve the equation for b: 3b = 12 b = 3 · 12 b = 36 describe the mistake that arnold made.

Can someone tell me if this is perpendicular? !