All you have to do is multiply the least commen donomenator by 2 and that will be your answer
Distribute on the left side
7.4a+22.2=3.2a+43.2
Subtract 3.2a from both sides
4.2a+22.2=43.2
Subtract 22.2 from both sides
4.2a=21
Divide both sides by 4.2
a=5
The diver will hit the water when the height is zero, so we will want to set our height function equal to zero
0 = -4t^2 + 11t + 3
we will then factor to find out value of t that make the function equal to zero
0 = (-4t - 1 ) ( t - 3 )
This means our function equals zero when t = -1/4 s and t = 3 seconds
Since time cannot be negative, our final solution is t = 3 seconds