Question

The total height of three trees is 15 meters. Tree A is 1 m shorter than tree B and tree B is half as tall as tree C. How tall is tree A ?

Answer 1

A : Tree A

B: Tree B

C : Tree C

Total height of the 3 trees is 15m

A + B + C = 15

A is 1m shorter than B

A = B-1

B is half as tall as C

B = C/2

We have 3 equations

A + B + C = 15 (1)

A = B-1 (2)

B = C/2 (3)

Add subtract (2) to (1)

A + B + C = 15

-

A - B = -1

___________

2B +C = 16 (4)

Solve for C

C = 16-2B

Replace C = 16-2B in (3) and solve for B

B= C/2

B= (16-2B)/2

2B = 16-2B

2B+2B=16

4B=16

B=16/4

B= 4

Replace B=4 on (2) and solve for A

A= B-1

A=4-1

A=3

Replace A=3 and B=4 in (1) and solve for C

A+B+C=15

3 + 4 + C= 15

C=15 -3 - 4

C= 8

A=3,B=4,C=8