Answer:The number of text messages sent by his sister=162
Explanation:
Step 1
The ratio of number of text messages sent by Lucas to the number of text messages sent by his sister =4 to 9= 4:9
Number of text messages sent by Lucas =72
Total ratio is given as 4+ 9= 13
Step 2
such that the total number of messages sent by Lucas and by his sister will be calculated as
Ratio of text messages sent by Lucas/ total ratio x Total messages = Number of text messages sent by Lucas . Let X = Total number of messages
4/13 x X = 72
X=72 x 13 / 4 =234
Therefore, The number of text messages sent by his sister= ratio of text messages sent by his sister/ Total ratio x Total number of messages =
9/13 X 234= 162 messages