If `a/b=c/d` and a,b,c,d are positive numbers, then which of the following statement are true?

Take 5 pieces of the card paper. Write the following statements one on each paper. (a+b)/b=(c+d)/d a/c=b/d a/b=(ac)/(bd) c/d=(c-a)/(d-b) a/b=(rc)/(rd) a,b,c,d are positive mumbers nd a/b=c/d is given. Which of the above statement are true and false, write at the back of each card, if false explain why.

If A = {a, b, c, d, e} B= {c, d, e, f}, C = {b, d}, D = {a, e} then which of the follwing statements are true and which are false : C sube B

If A = {a, b, c, d, e} B= {c, d, e, f}, C = {b, d}, D = {a, e} then which of the follwing statements are true and which are false : D sube B

If A = {a, b, c, d, e} B= {c, d, e, f}, C = {b, d}, D = {a, e} then which of the follwing statements are true and which are false : C sube A

If A = {a, b, c, d, e} B= {c, d, e, f}, C = {b, d}, D = {a, e} then which of the follwing statements are true and which are false : B sube A

If A = {a, b, c, d, e} B= {c, d, e, f}, C = {b, d}, D = {a, e} then which of the follwing statements are true and which are false : A sube D

If A = {a, b, c, d, e} B= {c, d, e, f}, C = {b, d}, D = {a, e} then which of the follwing statements are true and which are false : D sube A

If A = {a, b, c, d} and B = {1, 2, 3}, then which of the following is a relation from A to B?