Can someone help me do this

Find the difference (8ab+a+2) - (3ab+6)

Solve this system of equations. 12x − 18y = 27 4x − 6y = 10

Write a polynomial function f of least degree that has rational coefficients, a leading coefficient of 1, and the given zeros. 3, 4+2i, 1+(sqrt)7 the answer is supposed to be: f(x)=x(^5)-13x(^4)+60x(^3)-82x(^2)-144x+360 what am i doing wrong?