A school's two sports fields, field A and field B, both have dimensions x yd by x yd. The school decides to make field A and field B each 5 yd wider, and to make field B 10 yd longer. Find a simplified expression for the ratio of the new area of field B to the new area of field A. Find the value of this expression if the dimensions of the fields are 49 yd by 49 yd.