Can someone Please help me solve this Physics problem?

A projectile was fired horizontally from an unknown height and the measured value of the range was x = 10 meters. Then the height was increased by 10 cm and the value of x was measured to be 11 meters. Determine: (a) The initial velocity of the projectile; (b) The initial height of the projectile corresponding to x = 10 meters; and (c) The range of the projectile if the height is doubled from the initial height.