What is the question? Please give more details.
The answer or number that you are looking for is -6.4. You can get this by dividing 3 by 5 which is equal to 0.6. Next you would subtract 7 to reverse the act of having added it. This will give you -6.4 which is what you are looking for.
Area of a triangle is A= 1/2 b x h and Area of a parallelogram is A=b x h. So I would say the area of a triangle is half of the area of a parallelogram. Or a parallelogram is double the area of a triangle.