Well just substitute y (the first equation) into the second equation.
So
5x-4(5-3x)=-3
Then just solve the equation from there.
5x-20+12x=-3
17x=17
x=1
and if you need y, y=2
18. It is 18 because when you multiply 2x2 plus 4 x2 plus 2 x3 you get 4 plus 8 plus 6 = 18
Simple, use PEMDAS and then do your simple math and then your answer should be 86922.56604
Like terms are going to have the EXACT same variables....or they can just be constants with no variables.
x^2 and 3x^2 are like terms
x^2 and x^3 are not like terms
8 and 9 are like terms
8x and 9y are not like terms
so ur like terms in ur problem are : 2y^3 and y^3
