1/7 of all students achieved great success in the written exercise in mathematics. 3/7 very good success. 2/7 good success, while 4 students achieved sufficient success. How many students did the writing exercise?(fractions)

x = 28

Step-by-step explanation:

Let the total number of students = x

x/7 + 3x/7 + 2x/7 + 4 = x If that is all there is.  If it isn't the problem can't be done. Combine like terms.

x(1 + 3 + 2)/7 + 4 = x

x (6/7) + 4 = x                       Subtract 6x/7 from both sides

4 = x - 6x/7

4 = 7x/7 - 6x/7                     Combine

4 = 1/7x                                Multiply both sides by 7

4*7 = 7x / 7

x = 28

the answer is b.)

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