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In each parallelogram, the opposed sides are congruent.
The sides AB an CD are opposed; so you write this equation
4x + 1 = 7x - 5.
Simplify it and find x
1 + 5 = 7x - 4x
6 = 3x
x = 6/3 = 2.
Now you calculate each side length, using given formulas.
Solved (which means that the way is shown and that you are fully instructed).
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Comment from student : ok so what would be the correct final answer for the other 2 sides?
My response : In your post, you have formulas expressing the side lengths via x.
Substitute the value x= 2 into these formulas and calculate the length of each side.
Keep in mind that in parallelogram the opposite sides are congruent, i.e. have equal length (the same length).