SOLUTION: if the length of a rectangle is 3 inches longer than the width and the perimeter of the rectangle is 78. what is the equation involving only the length? also solve the equation fin

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Let l-Length of rectangle
Length(l)=Width(w)+3 subtract 3 from both sides
l-3=w+3-3 or
w=l-3
Now we know that the perimeter =2l+2w or
78=2l+2(l-3) get rid of parens
78=2l+2l-6 add 6 to both sides
78+6=2l+2l-6+6 collect like terms
4l=84 divide both sides by 4
l=21-----------------------------------length of rectangle
w=l-3=21-3=18----------------------------width of rectangle
CK
2*21+2*18=78
42+36=78
78=78
Length is 3" longer than width
21 is 3 more than 18

Hope this helps----ptaylor