The last part to the last math question I posted

I forgot to add this when I posted before.

For my equation, I got y=0.3x+66.

I'm supposed to approximate the life expectancy for women born in the US in 1994.

X in the equation is representing year of birth.
Y in the equation is representing the corresponding life expectancy.

Every time I plug "1994" into my equation, I get an answer in the 500's, which is obviously impossible in life expectancy. What am I doing wrong?

Because the 66 in your equation is wrong. y = 0.3x + c, and we know when x = 1940 then y = 66, c has to be -516, ie
y = 0.3x - 516.
A good check: plug in x = 1970 and you get y = 75 which I think was the other point on the graph you already knew.
Now try putting in 1994

In your original question you said that 66 was a year - I assume this is 1966. Try plugging in 94 for the year