Which measure is equivalent to 2.5 liters? '

For each proportion find the unknown number x 1/5/8=×/15

When you answer this can you explain

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?