find the value of x for which abcd must be a parallelogram

Answer:
The answer is x=1.
Step-by-step explanation:
By definition of parallelograms:
Parallels lines have the same length, in this case:
BC = AD
//Replace with the values
4x + 7 = x + 10
//subtract 7 on both sides of the equation.
4x + 7 - 7 = x + 10 - 7
4x = x + 3
//subtract x on both sides of the equation
4x - x = x + 3 - x
3x = 3
//divide by 3 both sides of the equation
3x/3 = 3/3
x = 1