Fill in m and n with numbers then minus by one
90 books would be left I believe I just took 250/9 since it would take 9 quarters to make $2.50 and since 75% was gone that would mean 25% is left so your answer is 90 unless it’s not but I believe it’s right.
13 + 3i
15 - 6i - 2 + 9i → Sum
collect like terms
(15 - 2) + ( - 6i + 9i) =13 + 3i