How do I find the measurement indicated in these problems.

13. In parallelograms, adjacent angles are always supplementary. This means that angles that are right next to each other will always add up to 180.

So for this one, the two given angles add up to 180, creating this equation:

7x - 4 + 9x - 8 = 180

this can be simplified to x = 12

substitute x into <D to get <D = 100

since we know that <D and <A are supplementary, subtract m<D from 180 to get <A = 80

14. In parallelograms, opposite angles are always congruent, this means that in this problem <C and <A are equal to each other

so we can create an equation: 9x + 13 = 11x - 3

solve this to get x = 8

substitute 8 into <C's equation to get <C = 85

Since <C and <B are adjacent, subtract <C from 180 to get <B = 95

15. <J and <L are opposite to each other, so we know they are congruent

this means we can create an equation: 2 + 24x = 26x - 2

solve this to get x = 2

plug this into the equation for <J

you get <J = 50

16. In parallelograms, lines that are opposite to each other are always congruent. So this means that lines JM and KL are congruent

this means that we can create an equation of 2x - 15 = x - 4

solve this to get x = 11

plug in x to the equation for KL

you get KL = 7