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.
3(X)+X=190000 is how you'd find the answer the answer is 47,500
Y=mx+b
x=number of newspapers
37.5 earned for 5 newspapers
37.5=5m+b
earned 75 and deliverd 20 newpapers
75=20m+b
we have
37.5=5m+b and
75=20m+b
multiply first equaiton by -1 and add to other equaiton
-37.5=-5m-b
<u>75=20m+b +</u>
37.5=15m+0b
37.5=15m
divide both sides by 15
2.5=m
sub back to find b
75=2.5(20)+b
75=50+b
minsu 50 both sides
25=b
y=2.5x+25 is lnear funtion