We can use completing the square.We add 16 and subtract 7 to both sides. Now we get m^2+8m+16=9. The left sides becomes (m+4)^2=9. Taking the square root of both sides and subtracting 4 we get -1 and -7.
so you are going to use the Pythagorean theorem on the smaller triangle to find the connecting side's length

now you can find the bigger triangle's hypotenuse

c=4
Urface area = area of the square + area of the 4 triangles
= 6*6 + 4(1/2*6*6)
= 36 + 4 * 18 = 108 sq cms
3x + 28
We can combine 7x and -4x because they are like terms. 7x -4x is equal to 3x. Now we rewrite the expression as 3x + 28.