Given :
Spider man has $350 in his account and his earnings $25 per day.
Batman has $200 in his account and earns $35 per day.
To Find :
After how many days, d, will Batman have more than Spider man .
Solution :
Let , after x days they both have same amount .

So , at 15th day they both have equal amount .
Therefore , after 15 days i.e in 16th day batman have more money than spider man .
Hence , this is the required solution .