I need a little help with my math, so here's the chart and questions.

Instant Messenger Abbreviations
L8R : 48/100
Lol : 26/100
Brb : 19/100
CUL8R : 7/100

a. What fraction of these students uses LOL or CUL8R when using Instant Messenger?
b. What fraction of these students uses L8R or BRB when using Instant Messenger?
c. What fraction more of these students write L8R than CUL8R when using Instant Messenger?