In your question where ask to find the Standard Normal Distribution of the following:
give probabilities for 0<Z<infinity.
For these ranges, you can read directly, for example,
P(Z<1.96)=0.975.
So for #1, you read directly on the line 1.3 and column 0.03.
For #2, we note that the distribution is symmetrical about Z=0, so
P(Z<-2.33) is the same as P(Z>2.33)
which again is the same as
1-P(Z<2.33) because we know that the area under a probability distribution function adds up to 1.
For the remaining questions, work is similar to #2.
The error is in the second step they subtracted 3 from both sides but it was a 3x, which you can not do.
Correction.
9x+18+3x=1
12x+18=1
12x=-17
x=-17/12
Complete Question:
The local Farm Market sells peppers at five for $2.25. Write an equation that relates the number of peppers, n, and the cost, C.
Answer:

Step-by-step explanation:
Given

Required
Determine the relationship between C and n

Divide both sides by 5, to get the cost of 1 pepper



Multiply both sides by n to get the cost of n pepper


So, we have:

-ax-20=-14
add 20 to both sides
-ax=6