Question 1146620
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(1) The perimeter is twice the length plus twice the width: {{{P = 2l+2w}}}<br>
(2) The length is 6 inches less than 3 times the width: {{{l = 3w-6}}}<br>
Substitute (2) in (1): {{{P = 2(3w-6)+2w}}}<br>
(3) The perimeter is given as 28 inches: {{{28 = 2(3w-6)+2w}}}<br>
Solve that equation for the width w using basic algebra; then use (2) to find the length.<br>
That's a good solution using formal algebra; and using the formal algebra to find the solution is good practice.<br>
But if a formal algebraic solution is not required, guess and check is the fastest way to the answer.  The perimeter is 28 inches, so length plus width is 14 inches.<br>
Try combinations of length and width with a sum of 14 and find which pair satisfies the condition that the length is 6 less than 3 times the width:<br>
1 and 13: 3(1)-6 = -3 nonsense
2 and 12: 3(2)-6 = 0 no...
3 and 11: 3(3)-6 = 3 no...
4 and 10: 3(4)-6 = 6 no...
5 and 9: 3(5)-6= 9 YES! DONE.