Answer:
98
Explanation:
Solution 1, (quick)
When enlarging by a scale factor, the shape's area is multiplied by the scale factor squared.
3.5*7*2^2=98
This works because for a rectangle width x and length y, width 2x and length is 2y, area is 4xy compared to area xy originally.
Solution 2, (technical)
Scale factor of 2 means multiplying by 2
3.5^2=7
7*2=14
7*14=98