I believe the answer is C 1,300
To find the value of x, bring the variable to the left side and bring all the remaining values to the right side. Simplify the values to find the result.
Must do multiplication first....
-2/5 - 3/7 x 7/10
-2/5 - 21/70 (I'll reduce 21/70)
-2/5 - 3/10
Now you have to find a common denominator and subtract
-35/50 = -7/10......is what I get
First you had to switch sides of equation.

Then you divide by two from both sides of equation form.

Simplify.

Next, subtract by i from both sides of equation form.

Finally, simplify by equation.

Final answer: 
Hope this helps!
And thank you for posting your question at here on brainly, and have a great day.
-Charlie