I want to know what my professor meant by the Q$4$ comments. I know I didn't fill in the dialogue box, but i need to understand the rest of the comments for Q$4$ and also what the dialogue box would be

Q$4$b $-$ the profit$/$loss $=$ gallons x $($spot price contract price$)=($$$1,299,300).$

Q$4$c $-$ the interest on the floating $=$$$900$M x $4\mathrm{.}5\%.$