5 brownies and 15 cookies.
Working
4 plates —> 2B + 6C
1 plate —> 2/4B + 6/4C
10 plates —> 5B + 15C
188
141 divided by 3 is 47 so 47 times 4 is 188
112 Seats/ 7 Seats= 16 Total Rows
70Seats / 7Seats = 10 Full Rows
16-10=
6 Remaining Rows that tell us that there are a total of 42 empty seats.
It is true, they are congruent by doing a proof. You have to divide the trapezoid into 2 equal triangles. Then you can prove it. They are congruent since corresponding parts of congruent triangles are congruent.