Answer:
y= 10
Step-by-step explanation:
-3x-5y=4
+3x +3x
-5y=7x
+5y +5y
-1.5/2
In the standard form of the equation
The middle line =k
For our given problem
f(t) = 40cos (80t + 20)
On comparison we get k=0
Hence middle line=0