It is 30, 40, 50, but you have to use the equation for right triangles, which is a^2 + b^2= c^2. You fill in the equation 30^2 + 40^2= 50^2. Then you get 900+1600=2500. Then you add it together and you get 2500=2500.
The answer is 175 square inches because you have to multiply 5in•7in to get 35inches per picture and since there are five you have to multiply by 35•5=175