SOLUTION: Hi, I need some help with 7th grade math homework. I have to use equations to find the measurements of other sides of triangles and rectangle using known info. a)The largest sid

Algebra ->  Formulas -> SOLUTION: Hi, I need some help with 7th grade math homework. I have to use equations to find the measurements of other sides of triangles and rectangle using known info. a)The largest sid      Log On


   

Question 822702: Hi, I need some help with 7th grade math homework. I have to use equations to find the measurements of other sides of triangles and rectangle using known info.
a)The largest side of a triangle is six more units than the smallest side. The third side is twice the smallest side. If the perimeter of the triangle is 25 units, write and solve an equation to find the lengths of all three sides of the triangle.
b The length of a rectangle is (x+3)inches long, and the width is 3 2/5 inches.If the area is 15 3/10 square inches, write and solve an equation to find the length of the rectangle.
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
(a)
Let the smallest side = +s+
given:
largest side = +s+%2B+6+
the remaining side i= +2s+
--------------------------
+P+=+25+
+P+=+s+%2B+s+%2B+6+%2B+2s+
+P+=+4s+%2B+6+
+25+=+4s+%2B+6+
Subtract +6+ from both sides
+4s+=+19+
+s+=+19%2F4+
--------------
check the answer:
+25+=+19%2F4+%2B+19%2F4+%2B+6+%2B+2%2A%2819%2F4%29+
+25+=+38%2F4+%2B+24%2F4+%2B+38%2F4+
+25+=+100%2F4+
+25+=+25+
OK
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(b)
+A+=+%28+x%2B3+%29%2A%28++3+%2B+2%2F5+%29+
+A+=+3x+%2B+9+%2B+%282%2F5%29%2Ax+%2B+6%2F5+
+A+=+15+%2B+3%2F10+
+15+%2B+3%2F10+=+3x+%2B+%284%2F10%29%2Ax+%2B+9+%2B+12%2F10+
Multiply both sides by +10+
+150+%2B+3+=+30x+%2B+4x+%2B+90+%2B+12+
+34x+=+153+-+90+-+12+
+34x+=+153+-+102+
+34x+=+51+
+x+=+51%2F34+
+x+=+1.5+
--------------
The length is
+x+%2B+3+=+1.5+%2B+3+
+x+%2B+3+=+4.5+
The length is 4.5 inches or 4 1/2 in mixed numbers
-----------
check:
+A+=+3.4%2A4.5+
+A+=+15.3+ or +15.3+=+15+%2B+3%2F10+
OK
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I hope the switching between decimals
and fractions doesn't confuse you