college algebra
posted by je on .
1/4t + 3/5= 2/5  t

Is it
(1/4)t or 1/(4t)? 
(1/4)t

d/dx(sinx+cosx)

(1/4)t + 3/5= 2/5  t
=> (5/4)t + 3/5 = 2/5
=> (5/4)t = 1/5
=> t/4 = 1/25
=> t = 4/25
Strictly the equation should read
(d/dx)(sin(x) + cos(x))
=> (d/dx)sin(x) + (d/dx)cos(x)
=> cos(x)  sin(x)
The differentials of sin and cos should be learned. You can demonstrate the results by differentiating their respective series