ABC and DEF are similar
so
AB/AC = DE/DF
30/24 = 5/x
30x = 24 * 5
30x = 120
x = 4
Answer
Group up the like terms and combine them
2x^2 and -7x^2 add up to -5x^2
6x and 2x add up to 8x
1 and -3 add up to -2
We end up with -5x^2 + 8x - 2
