Using a system of equations, it is found that David is 12 years old.
<h3>What is a system of equations?</h3>
A system of equations is when two or more variables are related, and equations are built to find the values of each variable.
The variables are given as follows:
- Variable z: Rebecca's age.
David is three times younger than the dad and twice as old as Rebecca, then:
Rebecca is 30 years younger than the dad, hence:
z = y - 30.
Then, since x = 2z and z = y - 30 and y = 3x, we solve for x to find David's age.
x = 2(y - 30)
x = 2(3x - 30)
x = 6x - 60
5x = 60
x = 60/5
x = 12.
David is 12 years old.
More can be learned about a system of equations at brainly.com/question/24342899
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Question 21
Selling price = 18 + 18 x 36/100
Question 22
Discount price = 80 - 80x10/100
Selling price = discount price + discount price x 7/100
Answer:
870.497 ÷ 0.823=1.057 so to the nearest whole number it would be 1
Step-by-step explanation:
cause 0-4 numbers are rounded down
00.7 is the value
(It’s not allowing me to post cuz it’s short)
Caleb - c
Kyras - k
k+c=37
c=2k-4
k+(2k-4)=37
3k=41
k=41/3= ~13.67 years old
c=37-k
c=(111-41)/3
c=70/3=~23.33 years old