12a - 7 + 4a + 8

what is the answer

Aman steps out of a plane at a height of 4,000m above the ground falls 2,000m very quickly and then opens his parachute and slowly falls the remaining 2000m to the ground what height above the ground would be the best choice for a reference point

How can you decide witch operations to use to slice a two step equation

What is the standard form of -5x^2+2x^4-11+x^3+3x