Answer:
Son's Age: 11
Mary's Age: 33
Step-by-step explanation:
Let set Mary and her son as variables,
M = Mary's age
S = Mary's son age
<u>Breakdown:</u>
"Mary is three times as old as her son"
M = 3S
"In <em>12 years</em>, Mary's age will be one less than <u>twice her son's</u> age"
M <em>+ 12</em> = <u>2</u>(S <em>+ 12</em>) - 1
we add 12 to both sides as it will be in 12 years for both
We know that M = 3S, so we plug this in
3S + 12 = 2(S + 12) - 1
Now solve for <em>S (son's age),</em>
3S + 12 - 12 = 2(S + 12) - 1 - 12
3S = 2(S + 12) - 13
3S = 2S + 24 - 13
3S - 2S = 2S - 2S + 24 - 13
S = 24 - 13
S = 11
To find <u>Mary age</u>, plug in her son age ,
M = 3S
M = 3(11)
M = 33
Learn more about Substitution here: brainly.com/question/22340165
