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a classroom has 29 students. The number of girls is 4 less than twice the number of boys. find each number

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Nicole C. | Nicole- Marine BiologistNicole- Marine Biologist
5.0 5.0 (6 lesson ratings) (6)
1
In order to find the number of boys and girls you must understand the equation needed. 
 
The total number of girls plus boys is indicated as 29 students.
 
You then have to understand that there are "4 less than twice the number of boys". To start, add 4 to 29 which equals 33 to eliminate the "4 less". When it states twice the number of boys that is indicated that there should be 2x as many girls than boys. In order to view this as fractions, you would have 2/3 the class as girls and 1/3 as boys. 2/3 of 33 would be 22. Now that you have that you need to add back the "4 less" by subtracting 4 from your 22 be get 18. If there are 18 girls in the class you can then find the number of boys by taking 29-18 which would be 11 boys. 
 
double check your work:
 
18+11=19
(11*2)-4=18
 
Your answer:
18 girls
11 boys
Vivian L. | Microsoft Word/Excel/Outlook, essay composition, math; I LOVE TO TEACHMicrosoft Word/Excel/Outlook, essay comp...
3.0 3.0 (1 lesson ratings) (1)
0
Hi Vicki;
 
(x)+(2x-4)=29
x=number of boys
Let's combine like terms...
3x-4=29
Let's add 4 to both sides as we proceed to isolate x...
4+3x-4=29+4
3x=33
Let's divide both sides by 3...
(3x)/3=33/3
x=11
 
11 boys
(2x-4)=number of girls
[2(11)]-4=22-4=18 girls
Does 18+11=29
YES!
 
 
 
Robert J. | Certified High School AP Calculus and Physics TeacherCertified High School AP Calculus and Ph...
4.6 4.6 (13 lesson ratings) (13)
0
Mental math: Adding four girls, you have 2/3 of 33  = 22 girls. So, the answer is 22-4 = 18 girls and 29-18 = 11 boys.