What f(-1) means is that x=-1. Plug -1 in as x. Your new equation would be
f(x)=-3(-1)-14
Now, multiply -3 and -1 together
f(x)= 3-14
Subtract 14 from three
f(x)= -11
Answer: 84 dollars
Step-by-step explanation:
-10x - 3y = -18
(1)
-7x - 8y = 11 (2)
Multiply equation (1) by 8 and equation (2) by -3
-80x - 24y = -144
(1)
21x + 24y = -33 (2)
-------------------------------Add
-59x = -177
x = 3
Plug in x = 3 into -10x-3y=-18
-10(3) -3y =-18
-30 - 3y = -18
3y = -12
y = -4
Answer
(3, - 4)