Suppose b is the midpoint of ac. ab=5x and bc= 3x+4 find ac

If B is the midpoint of AC, then it means that AB = BC. 

Thus we can have 
5x = 3x + 4 

Solve for x. 
5x - 3x  = 3x - 3x + 4
2x = 4 
x = 2

AB = 5x so 5(2) = 10 
BC = 3x + 4 so 3(3) + 4 = 9 + 4 = 13

10 + 13 = 23 

AC = 23 

So AB = BC 

5x = 3x+4 

2x = 4

x = 4/2 

x = 2 

AB = 5x = 5*2 = 10 

BC = 3x+4 = 3*2+4= 6+4 = 10 

AC = AB +BC = 10 +10 = 20

AC = 20 

hope this will help you 

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