80+10x is the expression. To find the cost for 9 guests, simply plug in 9 for x. This becomes an equation reading 80+10(9)=170. The total cost for 9 guests is $170.00.
AAS means triangles are congruent if two pairs of corresponding angles and a pair of opposite sides are equal in both triangles. In this, A corresponds to E and B to D. BC and CD are congruent. Therefore the triangles are congruent