24/2.49=~10 so the ratio would be 1 : 10
Gonna do a little subbing here...
for 40 pgs of express proof reading....3 bucks per pg...c = 3
40(3) - 0.05(40(3)) = T
120 - 0.05(120) = T.....120 - 6 = T.....114 = T
so express proofreading cost 114
for 40 pgs of basic proof reading....c = 3.95
40(3.95) - 0.05(40(3.95) = T
158 - 0.05(158) = T....158 - 7.9 = T.....150.10
so basic proof reading costs 150.10
for 40 pgs of extended proof reading....c = 5
40(5) - 0.05(40(5) = T
200 - 0.05(200) = T....200 - 10 = 190
so extended proof reading is 190
no need to go further....the extended proof reading is gonna be ur answer...the best quality of editing that keeps it at 190
Making the assumption that your problem looks like this,

we use the distributive property to multiply: