How do you do this math problem? show you're work and explain !

 Area for question 1 is the equation (HxB)÷2 or 1/2BxH (that is how you find the area of a triangle.
To work out the Perimeter of the triangle you need to work out the value of each outter side. to work this out you need to use the equation a²+b²=c² where the value of c is the longest side in the right-angled triangle
1A)  22.5 inch²
1P) 5²+4.5²=c² = 25+20.25=c² = 45.25=c²
c=√45.25 = 6.73(2DP). The perimeter of this triangle is Base+2C which is 9+(6.73x2) = 9+13.46=22.46 inch

2A) 11x12=132÷2=66 inch²
2P) 11+12+13=36 inches

Y=-2x-6 is the answer