Sue is 7 years older than Bob. Three less than twice Bob's is Sue age, find bob and Sue's ages now?

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Answer 1 · 2017-09-21T02:18:30

Bob is #10#, Sue is #17#.

Let Sue #=S# and Bob #=B#

#S=2B-3#

#S=B+7#

Since #S=S#, then

#2B-3=B+7#

Do some algebra to figure out that

#2B - B = 7 + 3#

#B=10#

Since Sue is #7# years older than Bob, she is #17#.

Answer 2 · 2017-09-21T02:29:02

Bob is 10 Sue is 17

Let s = Sue's age
Let b = Bob's age

Sue is 7 years older than Bob so Sue is:

#s = b + 7# #[ 1 ]#

Three less than twice Bob's age:

#s = 2b - 3# #[ 2 ]#

You need to solve these simultaneously.

Substitute for #s# in equation [ 1 ]

#2b - 3 = b + 7#

Add 3 to both sides:

#2b = b + 10#

Subtract b from both sides:

#b = 10#

Substitute 10 for b in equation [ 1 ]

#s = 10 + 7 = 17#