what is the correct formula ? and solve problem and please show work?

The first formula is solved in terms of t (time) while the second is solved in terms of v_f (final velocity) and the third is solved in terms of a (acceleration).

Since the problem asks for the final velocity, you want the second formula.

Just plug in the other values:

v_0 or v_i : initial velocity <-- 25 (m/s)

a : acceleration <-- 7.0 (m/s²)

t : time <-- 6.0 (seconds)

Formula:

v_f = v_i + at

v_f = 25 + 7 * 6

v_f = 25 + 42

v_f = 67 m/s

at = v(f) - v(o)

7.0m/s^2 * 6.0 s = v(f) - 25 m/s 

42  m/s = f(f) - 25 m/s 

v(f) = 67 m/s 

they arre both the same formula, just rearranged.

V = 25 + 7•6 = 25+42 = 67 m/s