Help regarding subtraction

Hello guys,

I have been trying to work on excel and I've figured out some stuff lately but I am stuck at something for which I am posting here.

Here's a screenshot of the result I want to

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I want 70 & 50 from Column 1 to subtract from 50 & 40 from Column 2 and the result should be shown in the next column i.e Addition. How can I achieve this result can anybody please guide me in this ?


Thanks in advance,
Sabhay Tandon