數學題(英)－航空百大

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數學題(英)

發問:

代數↓↓↓↓↓↓↓the sum of three consecutive integers is 45 .what are these number?solve 7(x-1)-5(2-x)=3paul gets some 20-dollar nites and 50-dollar notes.it is known that he has $360 and the number of 20 dollar notes is grearter than that of 50 dollars by 4.find the 20 number of20 dollar notes .connie used 八分之三... 顯示更多代數↓↓↓↓↓↓↓ the sum of three consecutive integers is 45 .what are these number? solve 7(x-1)-5(2-x)=3 paul gets some 20-dollar nites and 50-dollar notes.it is known that he has $360 and the number of 20 dollar notes is grearter than that of 50 dollars by 4.find the 20 number of 20 dollar notes . connie used 八分之三 of her pocket money to visit the zoo.it is known that $75 remaind.how much pocket money did she have?

最佳解答:

#1 the sum of three consecutive integers is 45 .what are these number? let the three consecutive integers be x-1 , x,x+1 [it's easier to solve] x+(x-1)+(x+1)=45 3x=45 x=15 therefore, the three consecutive integers are 14,15,16 ======================================== 2.solve 7(x-1)-5(2-x)=3 7(x-1)-5(2-x)=3 7x-7-10+5x=3 12x=20 x=5/3 =========================================== 3.paul gets some 20-dollar nites and 50-dollar notes.it is known that he has $360 and the number of 20 dollar notes is grearter than that of 50 dollars by 4.find the number of 20 dollar notes . let the number of 20 dollar notes be x , so the number of 50 dollar notes be (x-4) 20x+(x-4)(50)=360 70x=560 x=8 so the number of 20 dollar notes is 8 =================================================== 4.connie used 八分之三 of her pocket money to visit the zoo.it is known that $75 remaind.how much pocket money did she have? assume she had $x pocket money x-3/8x =75 5/8x=75 x=120 so she had $ 120 pocket money

其他解答:

1.let y be the smallest number , that (y+1) is the smaller number , (y+2)is the biggest number , y+ (y+1) + (y+2) =45 3y+3=45 3y=42 y=14 so the number is 14 , 15, and 16. 2. 7(x-1)-5(2-x)=3 7x-7-10+5x=3 12x-17=3 12x=20 x=1&2/3 3. let 50y be the number of 50-dollar notes, that 20(y+4) be the number of 20-dollar notes , 50y+20(y+4)=360 70y+80=360 y=4 4+4=8 so there are 8 20-dollar notes. 4. let y be the money she has , y(1-3/8)=75 y5/8=75 y=120 so she has $120.|||||the sum of three consecutive integers is 45 .what are these number? x+(x+1)+(x+2)=45 3x+3=45 x=14 the three numbers are: 14,15,16 solve 7(x-1)-5(2-x)=3 7x-7-10+5x=3 12x=20 x=20/12= 5/3 paul gets some 20-dollar nites and 50-dollar notes.it is known that he has $360 and the number of 20 dollar notes is grearter than that of 50 dollars by 4.find the number of 20 dollar notes . Let x be the number of $20 notes, y be the number of $50 notes F1: 20x + 50y = 360 F2: x= y+4 Put F2 into F1: 20(y+4) + 50y = 360 70y + 80 = 360 70y = 280 y = 4 x = y +4 = 4+4 = 8 connie used 八分之三 of her pocket money to visit the zoo.it is known that $75 remaind.how much pocket money did she have? Let x be the money Connie has X x (1 - 3/8) = 75 5X / 8 = 75 5X = 600 X =120