Question 1168152
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The solution by the other tutor is fine; you should know how to set up and solve the problem using formal algebra in some way similar to his.<br>
But you can get some very good practice with logical reasoning skills by solving the problem informally.  Here is how this problem can be solved quickly without algebra.<br>
(1) In 3 years, Sheena will be 3 times as old as Melona.  That means her age 3 years from now will be a multiple of 3; and that means her current age is a multiple of 3: 3, 6, 9, 12, 15, 18, ...<br>
(2) A year ago, Sheena was 7 times as old as Melona.  That means her current age is 1 more than a multiple of 7: 1, 8, 15, 22, ...<br>
The smallest age that satisfies both conditions is 15.  See if that satisfies the conditions of the problem.<br>
CHECK:<br>
Sheena is 15; in 3 years she will be 15+3=18; so in 3 years Melona will be 18/3=6; so Melona is now 6-3=3.<br>
Sheena is 15; a year ago she was 15-1=14; so a year ago Melona was 14/7=2; so now Melona is 2+1=3.<br>
Everything checks....<br>
ANSWER: Melona is 3 and Sheena is 15.<br>