Make two equations for j = john and m = mary.
j + m = 32
j - 4 = 2m
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Solve for m in the first equation. Subtract j from both sides.
m = 32 - j
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Plug m into the second equation.
j - 4 = 2(32 - j)
Distribute 2 inside the parentheses.
j - 4 = 64 - 2j
Add 4 to both sides.
j = 68 - 2j
Add 2j to both sides.
3j = 68
Divide both sides by 3.
j = 22 2/3
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Plug j into the first equation.
22 2/3 + m = 32
Subtract 22 2/3 from both sides.
m = 9 1/3
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Mary = [tex] \boxed {9~ 1/3~years~old} [/tex]
John = [tex] \boxed {22~2/3~years~old} [/tex]
