On a biased dice, the probability of getting a 1 is 0.3 the dice is rolled 150 times how many ones would you expect to roll ?

What is the missing statement in step 4? ? rts ? ? vtu and ? rtu ? ? vts ? rts ? ? rvs and ? rtu ? ? stv ? vrs ? ? vru and ? usr ? ? usv ? vur ? ? vus and ? uvs ? ? sru