Algebra
posted by Joisey girl .
Scientists want to set up and test animals in the area for West Nile. The costs to test are $2,200 for setup plus $1.50 to administer each test.
Write an expression that gives the total cost to test x animals.
Hint: An expression is a combination of known and unknown values.

2200 + 1.50x

Thank you so much. How can We can find the average cost per animal by dividing total costs by number of animals.
Write an expression that helps solve the average cost per animal.
2200 + 1.50/x <<<would this be the answer 
You actually need parentheses around '2200 + 1.50x' when you are dividing to find the average. So (2200 + 1.5x)/x would be my answer. (I removed the 0 after 1.5 also, as 1.5 is the same number as 1.50.)

2xa(4xb  2x3 + 5x)