Câu 1 :Each of cars can take 8 people. How many cars needed to take 124 people?
Câu 2 : How many integer numbers between 200 and 300 are there for which the hundreds digit equals the sum of the other two digits?
Câu 3 : The average of five numbers is 20. The average of the five number is 18 when one of the numbers is chaned to 4. What is the orginal value of the changed number?
Câu 4 :A book has 250 pages starting at number 1. How many digits are there in the page numbers of the book?
Câu 5...
Đọc tiếp
Câu 1 :Each of cars can take 8 people. How many cars needed to take 124 people?
Câu 2 : How many integer numbers between 200 and 300 are there for which the hundreds digit equals the sum of the other two digits?
Câu 3 : The average of five numbers is 20. The average of the five number is 18 when one of the numbers is chaned to 4. What is the orginal value of the changed number?
Câu 4 :A book has 250 pages starting at number 1. How many digits are there in the page numbers of the book?
Câu 5 : Find A, if A is 3 less than the average of 48; 55; 29 and A. The value of A is…
Câu 6 : The sum of denominator and numerator of a fraction is 121 and the fraction is equal to 4/7. Find the denominator of the fraction?
Câu 7 : The sum of two numbers is equal to 77. If the first number is multiplied by 8 and the second by 6, the two product are equal. The larger of these numbers is…
Câu 8 : Which is the greatest 2 - digit number divisible by 2, 3 and 4?
Câu 9 : Calculate: (1 + 2/5) x 6/7.
Câu 10 : Give the number sequence: 1, 4, 7, 10, 13, … Find the 15th term of the number sequence.
Cho tử số của nó là \(x\)
Mẫu số của phân số đó là: \(x+5\)
Phân số đó có dạng: \(\dfrac{x}{x+5}\)
Mà giá trị của phân số này bằng \(\dfrac{6}{7}\) nên:
\(\dfrac{x}{x+5}=\dfrac{6}{7}\)
\(7\times x=6\times\left(x+5\right)\)
\(7\times x=6\times x+6\times5\)
\(7\times x-6\times x=30\)
\(x=30\)
Vậy tử số ban đầu là 30
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