These really confused me when I first learned them. Let's see what we can do.
a + t + d = 142
t = a - 8
d = 4a
Since Tom and Dale are both compared to Amanda, we can use those comparisons in an equation and figure out how much Amanda has. We do this using substitution.
a + (a - 8) + 4a = 142
a + a - 8 + 4a = 142
Now, remember that a variable by itself is ONE if that variable, but we don't call me 1 David.
6a - 8 = 142
We "move" the 8 by doing the opposite operation, since subtracting 8 and adding it results in 0.
6a - 8 + 8 = 142 + 8
6a = 150
Now, 6a is 6 times a and we divide by 6 because 6/6 = 1.
6a/6 = 150/6
a = $25
t = 125 - 8
t = $17
d= 4(25)
d = $100
Hope this helps!
