6.70 for paint brushes. for 2 is 6.70×2=$13.40
35-13.40=$21.60 left after 2 paint brushes
4.80×4=$19.20 for 4 tubes of paint
21.60-19.20=$2.40 left after 4 tubes of paint and 2 paint brushes
Δ = (8i)^2 - 4*(-25) => Δ = -36 +100 => Δ = 64 => x1 =(-8i + 8)/2 => x1 = -4i +4;
x2 = (-8i - 8)/2 => x2 = -4i-4; in this case, your solutions are complex conjugates.