Translate it up, translate it down, translate it to the right, translate it to the left, stretch it vertically, stretch it horizontally
First, replace f(x) with y.
So we have now:
y = 3x + 1
Next, switch the x and y.
We get:
x = 3y + 1
Finally, solve for y.
3y = x - 1
y = x/3 - 1/3
So, we have f(x) = 3x + 1, and the inverse of this function is:
<span>50-8t<90
50-90<8t
-40<8t
8t>-40
t>-5
Solutions should go to the right.
Mary probably was solving it as following
</span>50-8t<90
<span>-8t<90-50
-8t<40 (here, when she divided both sides by -8, she had to change sign < to the sign >)
But she did not change the sign, and got
t<-5
</span>
$13.20. ($10.75x1.08=11.29 $11.29x1.17=$13.20)
If I'm not mistaking parallel lines never touch