
Bradford T. answered 02/02/23
Retired Engineer / Upper level math instructor
Let b be Brody's age and j be Janet's age.
b = j+3
b+5 + j+5 = 65
j+3 +5 + j+5 = 65
2j +13 = 65
2j = 52
j = 26
b = 26+3 = 29
Kaylynn H.
asked 02/02/23Bradford T. answered 02/02/23
Retired Engineer / Upper level math instructor
Let b be Brody's age and j be Janet's age.
b = j+3
b+5 + j+5 = 65
j+3 +5 + j+5 = 65
2j +13 = 65
2j = 52
j = 26
b = 26+3 = 29
Wesley E. answered 02/02/23
Johns Hopkins University Mechanical Engineer
Hi Kaylynn, based on the word problem, you can create two equations. First we will create variables, where B will represent Brady's age, and J will be Janet's age.
From the first sentence, we know Brody is 3 years older than Janet, so B = J + 3 (Equation 1).
From the second sentence, we know in 5 years the sum of their ages will be 65, so (B + 5) + (J + 5) = 65 (Equation 2).
Let's first simplify Equation 2 so all the non-variables are on the right side of the equation.
B + 5 + J + 5 = 65
Add the two 5s on the left.
B + J + 10 = 65
Subtract 10 from both sides.
B + J = 55 (New Equation 2)
Now we have a few options to solve, but I will use the Substitution method for this example. From Equation 1, we know B = J + 3, so we will plug in 'J + 3' into the New Equation 2 in place of 'B'. You will get:
(J + 3) + J = 55
Then let's drop the parentheses and add the J's to get,
2J + 3 = 55.
Subtract out 3 from both sides.
2J = 52.
Divide both side by 2.
J = 26.
Since the question asks for Brody's age, we can use equation 1 again knowing Janet is 26.
B = J + 3
Plug in 26 for J.
B = 26 + 3 = 29
Brody is currently 29.
You can confirm you have the correct answer by plugging both J = 26 and B = 29 into Equation 2, and you will see you get a true result.
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