1/2 = 36/72
3/4 = 12/16
5/6 = 25/30
Let's write a system of equations. We will use D for Derek's age and S for Sarah's age:
D = 4S
(D - 2) + (S - 2) = 36
We can simplify the second equation:
D + S - 4 = 36
D + S = 40
Now we can use substitution to plug 4S in for D in the second equation:
(4S) + S = 40
5S = 40
S = 8
Sarah is 8 years old.
Answer:
20? i am not positive
Step-by-step explanation:
2x + 5y = 26....multiply by 3
3x + 4y = 26...multiply by -2
------------------
6x + 15y = 78 (result of multiplying by 3)
-6x - 8y = - 52 (result of multiplying by -2)
-----------------add
7y = 26
y = 26/7 (or 3 5/7)
2x + 5y = 26
2x + 5(26/7) = 26
2x + 130/7 = 26
2x = 26 - 130/7
2x = 182/7 - 130/7
2x = 52/7
x = 52/7 * 1/2
x = 52/14 which reduces to 26/7 (or 1 5/7)
solution is : (26/7, 26/7)