Question

3. Set-up and solve using a variable.
Betty is 3 times as old as Tim. Peter is 4 years older than Betty.
If the sum of their ages is 39, find Betty's age.​

Answer 1

Answer:

Betty b is 15 years old

Step-by-step explanation:

First, write a formula: b+t+p=A, where b is Betty's age, t is Tim's age, p is Peter's age and A is the total age.

Second, replace values: b=3t, which also equals b/3=t, because Betty is 3 times as old as Tim; b+4=p, because Peter is 4 years older than Betty; A=39, because that is the total sum, so you get b/3+(b+4)+b=39.

Simplify and solve for b, using basic algebra rules, so you get b=15. Betty is fifteen.

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