document.write( "Question 767200: John is being paid $864 to do a landscape job. It took him 6 hours less than he expected, so he earned $2 per hour more than he originally calculated. How long had he anticipated it would take to do the landscaping? \n" ); document.write( "
Algebra.Com's Answer #467484 by DrBeeee(684) ![]() You can put this solution on YOUR website! Let h = number of hours originally costed \n" ); document.write( "Let r = the rate at which the h hours were costed. \n" ); document.write( "Then we have \n" ); document.write( "(1) r*h = 864 or \n" ); document.write( "(2) h = 864/r \n" ); document.write( "When he finished he was paid $864 as he charged them, but he took 6 hours less which in effect increased the hourly rate r. In the end his pay was \n" ); document.write( "(3) (r+2)*(h-6) = 864 \n" ); document.write( "Equating (1) and (3) we get \n" ); document.write( "(4)(r+2)*(h-6) = r*h or after FOILing gives us \n" ); document.write( "(5) r*h - 6r + 2h - 12 = r*h or \n" ); document.write( "(6) 2h = 12 + 6r or \n" ); document.write( "(7) h = 6 +3r \n" ); document.write( "Now equate (7) and (2) to get \n" ); document.write( "(8) 3r + 6 = 864/r or after multiplying by r we get \n" ); document.write( "(9) 3r^2 + 6r - 864 = 0 or after dividing by 3 we get \n" ); document.write( "(10) r^2 + 2r - 288 = 0 which factors into \n" ); document.write( "(11) (r + 18)*(r - 16) = 0 \n" ); document.write( "Taking the positive root gives us \n" ); document.write( "(12) r = 16 \n" ); document.write( "Use (12) in (2) gives us \n" ); document.write( "(13) h = 54 \n" ); document.write( "Let's check this with (1) \n" ); document.write( "Is (16*54 = 864)? \n" ); document.write( "Is (864 = 864)? Yes \n" ); document.write( "Then after the job was finished he spent 54-6 or 48 hours on the job. He said that was, in effect, his original rate plus $2. Let's check this with (3). \n" ); document.write( "Is ((16+2)*(54-6) = 864)? \n" ); document.write( "Is (18*48 = 864)? \n" ); document.write( "Is( 864 = 864)? Yes \n" ); document.write( "Answer: He originally anticipated that it would take 54 hours to do the landscaping job. \n" ); document.write( " |