Ryan has the numbers 1–30 listed on individual index cards. If Ryan randomly selects 1 card, what is the probability that it will be a multiple of 3 or a multiple of 11?

multiples of 3 are 3n (3,6,9,12...)

number of terms=10
p(multiple of 3)=10/30
multiples of11 11n(11,22)
p(multiple of 11)=2/30
p(multiple of 11 or 3)=10/30+2/30=6/15