How is this sum solved please give detailed explanation - Physics - Basic Mathematics(Pre-requisite)

Question

How is this sum solved?please give detailed explanation

Debalina Deb · Accepted Answer

Dear student,
<img alt="" src=
"https://s3mn%20mnimgs%20com/img/shared/content_ck_images/ck_60963f159191a%20jpg"
style="width: 1023px; height: 803px;">

Regards,