Whats the x value of the solution to this system of equations
x=2y-4
7x+5y=-66

Pick the expression that matches this description: a polynomial of the 5th degree with a leading coefficient of 7 and a constant term of 6 (choice a) 7x^5+2x^2+6 (choice b) 7x^6−6x^4+5 (choice c) 6x^7−x^5+5 (choice d) 6x^5+x^4+7

An equation where variables are used to represent known values—function notation true or false

If the scale factor between two circles is 2x/5y what is the ratio of their areas?