by arif
(saudi arabia)
The sum of Mira and Shaheena is 40 years. After 10 years Mia will be twice as old as Shaheena. What is Mia's age. What is Shaheena's age?
Solution
Let m be Mira's age
Let s be Shaheena's age
The sum of Mira and Shaheena is 40 years.
The statement above gives the following equation
m + s = 40
After 10 years,
Mira's age will be m + 10
Shaheena's age will be s + 10
The problem also says that Mia will be twice as old as Shaheena.
The statement above gives the following equation
m + 10 = 2 × (s + 10)
m + 10 = 2 × s + 2× 10
m + 10 = 2s + 20
You now have a system of linear equation to solve
m + s = 40 equation 1
m + 10 = 2s + 20 equation 2
Use equation 1 to solve for m
m + s = 40
m + s - s = 40 - s
m = 40 - s
Replace 40 - s into equation 2
40 - s + 10 = 2s + 20
40 - s + s + 10 = 2s + s + 20
40 + 10 = 3s + 20
50 = 3s + 20
50 - 20 = 3s + 20 - 20
30 = 3s
Divide both sides by 3
30/3 = 3s / 3
10 = s
m + s = 40
m + 10 = 40
m + 10 - 10 = 40 - 10
m = 30
Shaheena is 10 years old. Mira is 30 years old
In 10 years Shaheena will be 20 and Mira will be 40. Mira's age will then be twice that of Shaheena.
Apr 03, 17 09:12 AM
Learn to divide using partial quotients. Understand the concept fast!
New math lessons
Your email is safe with us. We will only use it to inform you about new math lessons.
Apr 03, 17 09:12 AM
Learn to divide using partial quotients. Understand the concept fast!