Hey! Apologies that I can’t make this look nice because I’m on mobile.
To simplify this, we can multiply the denominator by its conjugate. For a imaginary function (a+bi), its conjugate would be (a-bi), so we can apply that here to multiply both sides by (2-i)/(2-i). This works because it simplifies to one. Then, we have our fraction as 4*(2-i)/((2-i)(2+i))=(8-4i)/(4-i^2)=(8-4i)/5
Feel free to ask further questions, and have a great rest of your day!
He will spend $66.3 because 78 times 15/100 (which is 15%) is 11.7, and since he reduces the food you will have to subtract 11.7 from $78, to get $66.3