Use Ga_thMath(u) (brainly doesn't allow me to type it) To use the app u need to take a pic of the problem and then it will process it and you'll get ur answer ASAP(most of the time). Many questions have been asked before so search it on brainly.
Answer:
a rational expression is an expression that has a RATIO in it
look at the word "RATIO"nal
a ratio is just a fraction...
so your question is "how to simplify fractions"
lots of approaches, this is one of them...
PRIME FACTOR the numerator and denominator

90 = 2 * 3 * 3 * 5
135 = 3 * 3 * 3 * 5
= 2/3 (the two 3's cancel and the 5's cancel)
Step-by-step explanation:
Sydney's age = x
Devaughn's age= 3x
So you get the equation:
x+3x=24
4x=24 (combine like terms)
x=6 (divide both sides by 4)