The slope is 3/1, which can be simplified to 3. Find it by traveling up 3 points and over 1 point form one intersection point to the next.
first speed --- x mph
return speed -- x+16 mph
6/x + 6/(x+16) = 1
times each term by x(x+16)
6(x+16) + 6x = x(x+16)
x^2 + 4x - 96 = 0
(x-8)(x+12) = 0
x = 8 or x is a negative
her first speed was 8 mph
her return speed was 24 mph
check:
6/8 + 6/24 = 1 , that's good!
Parallel lines have the same slope.
So I plug in the -5 and -4
-4 = 1/2(-5) + b
-4 = -2.5 + b
b = -1.5
So I get y = 1/2x - 3/2
Let x be white marbles, y be yellow marbles
x+y=54…(1)
x=3y - 6 …(2)
put (2) into (1)
(3y - 6) + y = 54
4y = 60
y=15
put y=15 into (1)
x + 15=54
x=39
so y=15 x=39
