Here the answer is 19/35
Step-by-step explanation:

We will apply BODMAS rule
In this rule multiplication comes before add and subtraction
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The exponent 4 needs to be applied to both 3 and x, so we would have:
3 * 3 * 3 * 3 * x^4.
9 * 9 * x^4.
81x^4
B-y is the another factor