The area of a paralellogram is bh
each dimention is multiplied by n
b turns to bn
h turns to hn
bh turns to (bn)(hn) or bnhn or bhn²
expression is bhnn or bhn² or bhn^2 (depends if the program will let you enter the exponent)
Y=12 because the triangles have proportional side lengths
I believe it is 3x+21 but i could be wrong :/ my explaination is -3 • -X would be +3x because it was distributed and -3 • -7 would be +21