Your answer would be 2.0 × 10⁴.
We can first write out the fraction to make it easier to see how to get the answer:

Because all terms in the numerator and denominator are being multiplied, we can just divide each term individually, which gives us:
2.8 ÷ 1.4 = 2

We know that this is true as the rule for dividing exponents with the same base is to subtract them, and 7 - 3 = 4.
Putting these two results together, we get the answer of 2.0 × 10⁴.
I hope this helps!