(x x y) a=xa x ya illustrates which property of exponents

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

What is the answer to this question? i'm a bit stumped. also how do i do it? 5(x - 4) = 2(x + 5)

What is the value of x in the equation7x+2y=48 when y=3