Answer:
d = 12
Explanation:
Apparently you want the value of d that satisfies √(4y-3) = d-y when y=7.
Solution
Substituting y=7, the equation becomes ...
√(4·7 -3) = d -7 . . . . substitute y=7
√25 = d -7 . . . . . . simplify root
5 +7 = d . . . . . . . add 7
d = 12