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maths!
發問:
1) 72 marbles are divided into two portions so that 7 times the smaller portion equals 5 times the bigger portion.Find the number of marbles in the smaller one.2)The cost of 24 books is $405. Among them,some cost $15 each and all the others cost $20 each.What is the number of books whose cost is $15?3)There are... 顯示更多 1) 72 marbles are divided into two portions so that 7 times the smaller portion equals 5 times the bigger portion.Find the number of marbles in the smaller one. 2)The cost of 24 books is $405. Among them,some cost $15 each and all the others cost $20 each.What is the number of books whose cost is $15? 3)There are 42 students in F.1A. The number of boys is 1/3 more than that of girls. Find the numbers of boys and girls respectively.
1. Let x be the smaller portion, and number of larter portion is 72-x 5* (72-x) = 7x 360-5x = 7x 12x = 360 x=30 Number of marbles in the smaller one is 30 2. Let x be the number of book cost $15, then number of book cost $20 = 24-x 15x + (24-x)*20 = 405 15x + 480 -20x = 405 5x = 75 x = 15 There are 15 books whose cost is $15 is 3. Let x be the number of boys, then number of girls = 42-x x = (42-x) * (1+ 1/3) x = 56 – 1.33x 2.33x = 56 x=24 Number of boys = 24, and number of girls = (42-24) = 18
其他解答:
good!|||||I believe you can finish the homework by yourself
maths!
發問:
1) 72 marbles are divided into two portions so that 7 times the smaller portion equals 5 times the bigger portion.Find the number of marbles in the smaller one.2)The cost of 24 books is $405. Among them,some cost $15 each and all the others cost $20 each.What is the number of books whose cost is $15?3)There are... 顯示更多 1) 72 marbles are divided into two portions so that 7 times the smaller portion equals 5 times the bigger portion.Find the number of marbles in the smaller one. 2)The cost of 24 books is $405. Among them,some cost $15 each and all the others cost $20 each.What is the number of books whose cost is $15? 3)There are 42 students in F.1A. The number of boys is 1/3 more than that of girls. Find the numbers of boys and girls respectively.
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最佳解答:1. Let x be the smaller portion, and number of larter portion is 72-x 5* (72-x) = 7x 360-5x = 7x 12x = 360 x=30 Number of marbles in the smaller one is 30 2. Let x be the number of book cost $15, then number of book cost $20 = 24-x 15x + (24-x)*20 = 405 15x + 480 -20x = 405 5x = 75 x = 15 There are 15 books whose cost is $15 is 3. Let x be the number of boys, then number of girls = 42-x x = (42-x) * (1+ 1/3) x = 56 – 1.33x 2.33x = 56 x=24 Number of boys = 24, and number of girls = (42-24) = 18
其他解答:
good!|||||I believe you can finish the homework by yourself
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