As hard as ABC

Algebra Level 1

If a + c = 7 a + c = 7 and b + c = 11 b + c = 11 , what is the value of

a + 2 b + 3 c ? a + 2b + 3c ?


The answer is 29.

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13 solutions

Fahad Usman
Sep 16, 2013

as it is given a+c=7 and b+c=11 so, a+2b+3c can also be written as (a+c)+(b+c)+(b+c)=7+11+11 = 29 ANS

Good :)

Arsala Mehr Ali - 7 years, 8 months ago
Kellen O'Brien
Sep 15, 2013

First, split the equation into something easier to work with. a+c+b+c+b+c. If you look closely, you see that you can substitute in the numbers 7 and 11 so it looks like this: 7+11+11. Then you add them together to get 29.

Savita Rana
Sep 19, 2013

if a+c=7 and b+c=11 and the value of a+2b+3c is a=7-c and b=11-c then putting the values of c = 7-c+{11-c}2+3c = 7-c+22-2c+3c = 7+22 = 29

Moderator note:

Good substitution approach. If you do not know what something is, try and express it in terms of something else.

2b+2c = 22 , a + c = 7

=> a+2b+3c = 29

Christian Đinh
Sep 16, 2013

(a+b)+(b+c)+(b+c)

a+2b+c=a+c+2c+2b =(a+c)+2(b+c) =7+2(11) =29

Randel Diaz
Sep 18, 2013

a=7-c b=11-c Substitute: a+2b+3c (7-c) + 2(11-c) + 3c 7-c + 22- 2c + 3c 29

Sai Chaturvedula
Sep 22, 2013

a+2b+3c = (a+c)+(b+c)+(b+c) = 7+11+11 =29

Hikmah Ramadhan
Sep 21, 2013

(b+c=11) x 2 2b+2c=22

so, a+c+2b+2c=7+22 a+2b+3c= 29

Antoine Bo
Sep 20, 2013

a+2b+3c= (a+c)+ (b+c) + (b+c) = 7 + 11 + 11 = 7 +22 = 29

Rajesh Mangena
Sep 18, 2013

Given data, a+c= 7------------------------Equation 1 b+c= 11----------------------Equation 2

Equation 1 + (2*Equation 2)= Answer = 29

Mosheh Yisra'el
Sep 17, 2013

B+C=11 if doubled it would be 2B+2C=22. So A+C=7 so if you add 2B+2C=22 to A+C=7 it will give you A+2B+3C which equals 29. This makes your answer 29.

Dim Dam
Sep 17, 2013

a+c=7 , b+c=11 has many solutions. so we make another equation and eliminate c variable. and we get a-b=-4 . now the possible number (a,b,c) are ..... (1,5,6), (2,6,5),(3,7,4),(4,8,3), (5,9,2)...... we can substitute these solution. Tadaaa.... and the result is same , its 29 ..

29

Rahmat Hadi - 7 years, 8 months ago

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