Well I don't know where inequalities would come in but the third length would be solved as follows.
a^2+b^2=c^2
10^2+18^2=424

Answer;

I hope this is correct, its what I would do if I had this equation.
Answer:
Jim can type 315 words in 3.5 minutes.
Step-by-step explanation:
90 x 3.5
Anthony can give 6 of his friends 3 stickers