I can't figure out last part please:

A spring whose length is 7 cm stretches at 1/2 cm per 1 kg of suspended weight.

1) When 3 kg of weight is suspended, how many centimeters is the total length of the spring?

7 + 1/2 x 3 = 8 1/2 cm

2) Express relation between suspended weight x and total length y as an equation

y = 1/2 x + 7

3) When length is 9.2 how many kilograms does suspended weight wegh?