Answer:
D.
Step-by-step explanation:
R + b = 49
b = 6r
r + 6r = 49
7r = 49
r = 49/7
r = 7 <== he has 7 red beads
b = 6(7)
b = 42 <== he has 42 blue beads
I'm pretty sure it's:
A right rectangular prism with length 15 inches, width of 8 inches, and height of 6 inches.
A cross section parallel to the base is a rectangle measuring 15 inches by 8 inches
A cross section perpendicular to the base through the midpoints of the 8-inch sides is a rectangle measuring 6 inches by 15 inches
Just visualize the rectangle