how old is sipho?

Question

temba is twice as old as sipho and silo is 5 years younger than sipho. the total of their ages is 31 years. how old is sipho?

Answer 1

Hi Alyssa,

 

To solve a word problem, I usually first write the equal sign and put what the word problem is asking for on the left side of the equal sign. Then I create an equation. Solve the equation and PRESTO you've got the answer.

 

Let's call Sipho's age X and put that on the left side of the equal sign. We know that if we add all three ages together, we will get 31, so put 31 on the right side of the equation. So the first step in building the equation will be:

 

X = 31  (it's incomplete and not correct, but it's a start.)

 

We have to put Temba's and Silo's age on the left and add it to Sipho's age to get 31. We know that Temba is twice as old as Sipho, so he would be 2X old and Silo's five years younger so his age would be X-5. Now our completed equation would be:

 

X + 2X + (X-5) = 31

or

Sipho's age + Temba's age + Silo's age = 31

 

Now just solve the equation:

X + 2X + (X-5) = 31

X + 2X + (X-5) = 31

               4X-5 = 31

                   4X = 31 +5

                     X = 36/4

 Sipho's age = X = 9 years old

                

Tom D.

Answer 2

T = 2Sipho                        eq. 1

 

Silo = Sipho - 5                  eq. 2

 

Silo + Sipho + T  = 31         eq. 3

 

substitute eq. 1 to eq. 3

 

Silo + Sipho + 2Sipho = 31

 

Silo + 3Sipho = 31                eq. 4

 

subsitute eq.2 to eq. 4

 

Sipho - 5 +3Sipho = 31

 

4Sipho = 36

 

Sipho = 9 years old