A bag contains 20 marbles, of which 4 are red. What is the probability that a randomly selected marble will be red? Select ALL that apply
A 115
B 4/20
C 2/10
05/2

Can someone me and do the problem plz so i can understand it more better

In triangle △abc, ∠abc=90°, bh is an altitude. find the missing lengths. ah=4 and hc=1, find bh.

At the beginning of 1974/75,2 years a man invested #2000 in a bank at 12.5% compound interest, if it degree #650 at the end of each two years to pay his son's school fees, after payment of interest to pay his son's school fees, how much did he have left at the beginning of the 1978/79 school year?