(NEED REALLY QUICKLY WILL GIVE BRAINLIEST)SHOW WORK AND MAKE SURE IT MAKES SENSE TO READ!!!

Carly is 3 times her brothers age.The sum of their ages is no more than 24 years.
1)Find an inequality that can be used to represent this situation.
a) x+3x<24
b) x+x+3<24
c) x+3x<24
d) x+x+3<24
Using the inequality you just found, find the oldest age that Carly's brother can be.