Of a rectangle are 7 parallel 8 perpendicular

1) x= Sally
x+5= Joe

In 15 years means to add 15 to Joe's age and that equals three times Sally's age (x).

(x+5) +15= 3x
x + 20=3x
20=2x
10= x

2) length= 2w+3
w= width

Perimeter= 2l + 2w
48= 2(2w+3) + 2w
48= 4w + 6 + 2w
48= 6w + 6
42= 6w
7=w

3) x= 1st integer
x+2= 2nd integer
x+4= 3rd integer

Since the integers are even, there has to be a difference of two between each one. 
5x= 3(x+2) +14
5x= 3x +6 +14
2x= 20
x=10

x+4= third consecutive integer = 10 + 4= 14

ANSWER: 1) 10 (second choice); 2) 7 (second choice); 3) 14 (third choice)

Hope this helps!  :)