Let n represent the number. You require
7n - 2n = 55
5n = 55 . . . . . . collect terms
n = 11 . . . . . . . divide by 5
The number is 11.
A =bh
Plug in values and solve for height (h).
A=3.36
b=2.8
3.36 = 2.8h
/2.8 /2.8
1.2 = h
Base and Height doubled:
b = 2.8
h = 1.2
2(2.8)=5.6
2(1.2)=2.4
Plug in new b and h to area equation given to find area:
5.6(2.4) = 13.44
Resulting parallelogram area = 13.44 ft^2
if ya asking for simpliicatio
remember that 
and
factor
Multiply the two values together to get 45 * 3/5 = 135/5 = 27
If $96,169 is their combined pay in one year then consider this...
800x12=9,600
Simplify 96,169 to 96,000...
Divide 96,000 by 9,600 = 10.0
then pretend we had divided 96,100 by 9,600 then your answer would be 10.01
