A spring balance has a maximum reading of 10 N and the length of the calibrated scale is 20 cm. A rectangular metal block measuring 10 cm by 2 cm is hung on the balance and stretches the spring by 15 cm . Calculate; the weight of the block. ; the mass of the block.

Hint:w=mg and g=10ms-²

3/4 the max stretch means 3/4 the max load: 3/4 * 10 = ___ N