Step-by-step explanation:
x=width of pool
2x=length of pool
the dimensions of the rectangle forming the walkway and the pool are x+4 and 2x+4
the area of this rectangle minus the area of the pool is 196 square feet
(2x+4)(x+4)-(x)(2x)=196
2x^2+4x+8x+16-2x^2=196
combine similar terms
12x+16=196
12x=196-16
12x=180
x=180/12
x=15 feet is the width of the pool
check: 34*19-30*15=196
646-450=196
196=196
