Correct answer is: actual wingspan of airplane is 6 inches.
Solution:-
We are given that wingspan is 'a' feet and tail span is 'b' feet in a scale drawing.
And we are also given that tail span is 2 inches that is b=2 inches and 
Let us plugin the b value in above equation.

Multiplying with 2 on both sides.
a=3X2=6 inches.
Hence actual wingspan of airplane is 6 inches.
5(x + y) - 3(x - y)
5x + 5y - 3x + 3y
5x - 3x + 5y + 3y
2x + 8y
5(x + y) - 3(x - y) = 2x + 8y
8(1/4x + 3/4) -3 =17
First distribute which results in (8/4x + 24/4)-3 =17.
Now just simply simplify it into (2x+6)-3 =17
Then you combine like term : 2x+3 =17
Subtract 3 on both sides : 2x=14
Finally divide 2 on both sides to isolate x: x=7