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F.1 Maths (Algebraic) 20點!!
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要列式.20點.Fast!!!>__
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2.Three times a number is ten more than half the sum of 15 and the number.Find the number. let x be the number, 3x-(15+x)/2=10 6x-15+x =20 7x=35 x=5 3.Susan is six years older than Janet.Twelve years ago,the age of Janet was half the age of Susan.Find their present ages. let x be hte age of janet, then susan's age is (x+6) 2(x-12)=(x+6)-12 2x-24=x-6 x=18 susan is 24 and janet is 18 4.There are 4 $10 coins and y $2 conis inside a bag.If the value of the conis in the bag is $58,find y. 4x 10 + 2y =58 2y=58-40 y=9 5.David bought 11 ball-points pens for $12 each and y pencils for $7 each.If David paid $237 in total,find y. 11x 12 + 7y =237 7y =105 y =15 6.Kiki's father is now 46 years old.8 years later,Kiki's father will be 2 times as old as her.Find the age of kiki now. let x be the age of kiki 46+8=2(x+8) 54= 2x+16 x=19 7.A wire with length 105 cm is cut into two.They are bent to form an equilateral triangle with lengths y cm and a square with lenghts 3y cm.Find the area of the square. 3(y) +3y(4) =105 15y=105 y=7 then the length of the square =3x 7 =21 the area =21x 21 =441 2011-02-10 17:19:09 補充： sorry question 2 is wrong here is the correct one 2.Three times a number is ten more than half the sum of 15 and the number.Find the number. let x be the number, 3x-(15+x)/2=10 6x-15-x =20 5x=35 x=7
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