Solve the following pair of linear equations by the elimination method and the substitution method :

3x + 4y = 10 and 2x - 2y = 2

Solve the following pair of linear equations by the elimination method and the substitution method :

3x - 5y - 4 = 0 and 9x = 2y + 7

Form the pair of linear equations in the following problem, and find their solutions (if they exist) by the elimination method :

Five years ago, Nuri was thrice as old as Sonu. Ten years later, Nuri will be twice as old as Sonu. How old are Nuri and Sonu?