Solve for a variable in terms of specific other variables

The derivative of eq1 below is diff(x(t), t) == diff(y(t), t). I am trying to use the solve function to solve for diff(y(t)) and the output should be diff(x(t)) but a message stating that Matlab is unable to find an explicit solution is displayed. How can you specify the value of diff(x(t)), for example diff(x(t)) = 5, so that the solve function will solve for diff(y(t)) as 5, or if the value is not specified the solve function should return diff(x(t)) rather than an empty sym?

syms x(t) y(t)  
eq1 = x == y+2;  
solve(diff(eq1),diff(y(t))) 

Answer 1

[Walter Roberson]

syms x(t) y(t)  
eq1 = x == y+2;  
deq = diff(eq1)

deq(t) = 

isolate(deq, diff(y))

ans = 

subs(ans, diff(x),5)

ans =