if S1={1,2,3,4,5,6,7,8,9,10,11,12,13,1 4,15,16,17,18,19,20}, S2={a, b,c, d}, S3={b, d,e, f}.The number of elements of (S1×S2) U (S1×S3) is​

Definitely

7.3

step-by-step explanation:

81+30=111180 minus 111=691/2×19=9.569÷9.5=7.263157895~7.3

The question is kind of confusing. if it's asking how many variations of answers can you give. then do 4^5 for your answer.this would be something like the first question could be a and the 2nd c or first b next c etc. if you can, ask the teacher for a better confirmation of what it's asking. if i'm assuming correctly what it's asking, it's 625 different variations.