Final answer:
Travis should increase each dimension of his deck by 3 feet.
Step-by-step explanation:
To increase the area of the deck by 50%, we need to find out by what factor the dimensions should be increased. Let's say the increase factor is 'x'.
The area of the original deck is 12 ft x 7 ft = 84 sq ft.
The area of the increased deck should be 50% more, which means 1.5 times the original area.
So, 1.5 * 84 = 126 sq ft.
The dimensions of the increased deck will be (12+x) ft x (7+x) ft.
Using the formula for area: (12+x)*(7+x) = 126.
Solving this quadratic equation, we get x=3.
Therefore, Travis should increase each dimension of his deck by 3 feet.