Identify the terms and like terms in the expression - x - 9x*2 + 12x*2 + 7

Find the perimeter of the triangle with vertices  d(3, 4),  e(8, 7), and  f(5, 9). do not round before calculating the perimeter. after calculating the perimeter, round your answer to the nearest tenth.  

Pls as soon as ! will award brainliest and 20 ! also the answer is not 22.5 degrees! find the value of x in each case:

The power generated by an electrical circuit (in watts) as a function of its current c (in amperes) is modeled by p(c)= -15c(c-8) what current will produce the maximum power?