Susan needs to drive miles to work. So far, she has driven miles. How many more miles must she drive?

Question

WHAT WILL IT BE?

Answer 1

if she needs to drive x miles

and she's already driven y miles

then she needs to drive x-y miles further

for example, if she needs to drive 100 miles

and she's already driven 90 miles

then she needs to drive 100-90=10 miles more