Help please :) Simplify each expression by combining like terms
A) x+3-5x+7+4y
B) 9ab+3b-7b+8ab-12
C) 9(4x-3)
D)5(2r+6)-12r
E) x(2y+7)+y(9+5x)
F) 3r+6r+5(3t-6)+6t

The ratio pv to nrt is plotted against pressure for ch4 at 0°c and 200°c. why does the curve for 0°c drop below the horizontal line for an ideal gas whereas the curve for 200°c does not?

What is the difference between the predicted value and the actual value

In the figure below, ∠dec ≅ ∠dce, ∠b ≅ ∠f, and segment df is congruent to segment bd. point c is the point of intersection between segment ag and segment bd, while point e is the point of intersection between segment ag and segment df. the figure shows a polygon comprised of three triangles, abc, dec, and gfe. prove δabc ≅ δgfe.