Explanation:
are you sure this is the right problem description ?
it does not make much sense to me.
7¹⁰ / 7⁴ = 7⁶
so,
7⁶ × 2 = 7⁹x7¹⁰/7^y = 7¹⁹x/7^y
2 = 7¹³x/7^y
2 = 7^(13-y) × x
we can move now things back and forth between the 2 sides, but as we have 2 variables, we have infinite many solutions (values for x and y that make the statement true.
so, I think your problem was actually
(7¹⁰)²/7⁴ = 7⁹*7¹⁰/7^y
with only 1 variable (y).
and that we can solve :
7²⁰/7⁴ = 7¹⁹/7^y
7¹⁶ = 7¹⁹/7^y
1 = 7³/7^y
so,
7³ = 7^y
therefore,
y = 3