21 because you just multiply the 2 numbers.
Solve for x
Divide both sides by -4
X= - 10/4
Now simplify by dividing top and bottom by 2
X= -5/2 or - 2 1/2
Cancel out the terms from one side first then do it for the other one. 4 example make x and individual by multiply the other side by 9 the evaluate. do the same for y
Just do 45x0.2 then take that number off of $45 thats your answer