Answer:
m<5= 75° Alternate angles are equal
m<6 = 180°-75°= 105 ° Angles on a straight line adds up to 180°
In a rectangle opposite sides are equal so AB= CD
2x+8= 3x+4
3x-2x=8-4 ( combine like terms, the signs will change since they are going over opposite sides)
x= 4
To solve for BC
AD= BC
x+17 ( we know that x=4)
4+17=21
Therefore BC= 21