Hi there!

Find the y-intercept by substituting in 0 for x:
f(0) = 0² + 2(0) + 3
Simplify:
f(0) = 3
3t shirts cost $18
1 shirt will cost 18/3t = 6/t
7t shirts will then cost = (6/t)*7t = 42
7t shirts will cost $42.00
Answer:
We have a total of 7200 plants.
The plants are distributed in one field with 18 rows of 200 plants and another field with 9 rows of N plants.
Where we want to find the value of N.
The total number of plants in the rows is:
"number of rows times number of plants in each row."
Then the total number of plants is:
18*200 + 9*N
And we know that we have a total of 7200 plants, then:
18*200 + 9*N = 7200
9*N = 7200 - 18*200 = 3600
N = 3600/9 = 400
Then the plants are distributed in 18 rows of 200 plants for one field, and 9 rows of 400 plants in the other field.
The first thing you want to do is isolate the (x)s.