Please help will leave good review and brainliest!

Step-by-step explanation:

For a parallelogram the diagonals (and half diagonals are equal. So we can say

3m=m+8

2m=8

m=4

And we can also say that

3m+m+8=2n-1+9

4m+8=2n+8

4m=2n

2m=n, and since we know m=4

n=2(4)

n=8

So m=4 and n=8

sss (side, side, side)

sas (side, angle, side)

asa (angle, side, angle)

aas (angle, angle, side)

hl (hypotenuse, leg)

c.

step-by-step explanation:

she should of added 9^2 and 12^2. that is because it is a^2+b^2=c^2. c^2 is the hypotenuse and should always be bigger than the other two numbers. which is why she should of added 9 squared and 12 squared together instead of 15 squared.