You have to subtract 3.2 from 3.5 to get x. 0.3+ 3.2=2.5 so x=0.3
Use substitution and substitute y into the other equation. One of the equations already gives you y in terms of x, so use that and substitute it into the other equation. y = 3x - 4
Plug into the other equation: -3y = -9x + 12
-3(3x-4) = -9x + 12
-9x + 12 = -9x + 12
This is an identity. So that means that any value of x makes this equation true. So B.
Ok,
f(0.35)= 7f/20
f(-5.2)=-26f/5
f(10)= 10f
f(-0.5)= -f/2
as for the last question I am not quite sure, sorry....hope I helped a little :)
Two thirds of the one cup that he added is 80g, so he went over by 48g