document.write( "Question 293909: Suppose that the weight (in pounds) of an airplane is a linear function of the total amount of fuel (in gallons) in its tank. When graphed, the function gives a line with a slope of 5.7.\r
\n" ); document.write( "\n" ); document.write( "With 47 gallons of fuel in its tank, the airplane has a weight of 2367.9 pounds. What is the weight of the plane with 20 gallons of fuel in its tank?
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Algebra.Com's Answer #212059 by Earlsdon(6294) $\"\"$ $\"About$

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You could start with the slope-intercept form of a linear equation: $\"W+=+mF%2Bb\"$ where: W = weight of plane and F = amount of fuel in gallons.
\n" ); document.write( "The slope, m, of the function is given as: $\"m+=+5.7\"$ so you can substitute.
\n" ); document.write( " $\"W+=+5.7F%2Bb\"$ You can find b, the W-intercept (or the weight of the plane with no fuel) by substituting the given fuel and weight amounts: W = 2367.9 and F = 47.
\n" ); document.write( " $\"2367.9+=+5.7%2847%29%2Bb\"$
\n" ); document.write( " $\"b+=+2100\"$ so the final equation is:
\n" ); document.write( " $\"W+=+5.7F%2B2100\"$ Now you can find the weight, W, of the plane when it has 20 gallons of fuel (F=20) in its tank.
\n" ); document.write( " $\"W+=+5.7F%2B2100\"$ Substitute F = 20.
\n" ); document.write( " $\"W+=+5.7%2820%29%2B2100\"$
\n" ); document.write( " $\"highlight%28W+=+2214%29\"$ lbs. \n" ); document.write( "

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