the sum of the ages of two siblings is 23 and the difference between their ages is 7. if frank is the older brother of beth, determine their ages by creating a pair of simultaneous equations and solving them.

Question

this is killing me i have been working on it for hours. can only us substitution method or elimination.

Answer 1

letting x be the age of frank
y be the age of beth;

x+y=23......(equation 1)
x-y=7 .......(equation 2)

using substitution method,
x=7+y

(7+y)+y=23
7+2y=23
2y=23-7
2y=16
y=8 x=7+8
=15
frank (x)=15years
beth (y) =8years

Answer 2

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