I believe 10% because 390 and 39 are exactly the same numbers almost
Answer:
a=50 b=20
Step-by-step explanation:
Call A and B the 2 present ages.
Ten years from now, A is twice as old as B -->
(A + 10) = 2(B + 10) (1)
Five years ago, A was 3 times as old as B -->
(A - 5) = 3(B - 5) (2).
Solve the system (1) and (2).
From (2) --> A = 3B - 15 + 5 = 3B - 10.
Replace this value of A into (1) -->
3B - 10 + 10 = 2B + 20 --> B = 20. Then,
A = 3B - 10 = 60 - 10 = 50.
Check
!0 years from now --> A = 60 and B = 30 --> A = 2B .OK
5 years ago --> A = 45 and B = 15 --> A = 3B. OK
Chapter : Linear equations
Lesson : Math for Junior High School
7x + 14y = 28
if want to find x and y, we must substitution value 0 to the equation x and y :
# If x = 0, then :
7x + 14y = 28
= 7(0) + 14y = 28
= 0 + 14y = 28
= 14y = 28 → y = 28/14
= y = 2
# If y = 0, then :
7x + 14y = 28
= 7x + 14(0) = 28
= 7x + 0 = 28
= 7x = 28 → x = 28 / 7
= x = 4
and that result was proven x = 4 and y = 2
Answer: 1. 1,0 2. -1,9 3.-20
Step-by-step explanation:
Answer: S1:E7 ; S2:E1 ; S3:E5
Step-by-step explanation:
What we know:
- 3 answers apply
- We need to find which answers go with each question
**A lot of info is problem-specific.
How to solve:
Since we only need to write the equations, we simply need to find the x and y variables, and the total.
Process:
Problem 1:
- Find the x 5.50
- Find the y 3
- Find the total 145
- Write equation 5.50 + 3 = 145
Problem 2:
- Find the x 2.50
- Find the y 0.75
- Find the total 25
- Write equation 2.50 + 0.75 = 25
Problem 3:
- Find the x 2
- Find the y 5
- Find the total 50
- Write equation 2 + 5 = 50
Solution: S1:E7 ; S2:E1 ; S3:E5