Answer: x+y=
Step-by-step explanation:
you would just write it out step by step explaining wht u need to do to solve the question
Sorry but, question is not completely seen
3/7 = 9/x
cross multiply because thats how u solve proportions
(3)(x) = (7)(9)
3x = 63
x = 63/3
x = 21
and if u will notice : 3/7 and 9/21 ....9/21 reduces to 3/7....so these are equivalent fractions...because proportions are nothing but equivalent fractions