Do you want us to answer or simplify?
Simplify:=−18x^7 y^3 + 21x^5 y^4+ 15x^2 y^5
3[x+3(4x-5)]=15x-24; x+12x-15=5x-8 (divide both sides by 3); 8x=7 (move all the x's to one side), x=7/8
1400, as 1200 + 200 = 1,400 and 1600 - 200 = 1400.
The missing value is 6 so 2/5 = 6/15
If you are finding the perimeter I believe you would just add up the four sides, getting 46
