If `x%` of `y` is `13x,` then find the value of `y`

If x% of 2000 = 600, then find the value of x.

If x% of 350 is 21, find the value of x.

If 3x + 5y = 21 and 2x +3y = 13 , then find the values of x and y .

If x^2+y^2-4x-6y+13=0 , then find the value of (x+y):(y-x).

If the solution of pair of linear equation 2x - 3y = 13 and 7x - 2y = 20 is x = 2 and y = - 3, then find the value of m for which y = mx + 7.