Question

find the largest numbe which extly divids 280&1245 leving remainder 4&3 respectively

Answer 1

According to question
since 4 is the reminder in 280
so subtract 4 from 280
which results 280-4=276
therefore 276 is the largest number which exactly divides 280 leaving the reminder 4.
similarly
1245-3= 1242
therefore 1242 is the largest number which exactly divides 1245 leaving the reminder 3