I have a basic maths question that im seeking to find an easy way to solve?

It is question three on this test - i got 11.25 grams per cube when the block of cheese is divided up into the required proportions - but is there a formula for this? anyone else get this answer? a href="http://www.naplan.edu.au/verve/_resources/NAP08_num_y9_calc_web_v10.pdf" rel="nofollow"http://www.naplan.edu.au/verve/_resource…/a