Multiplying a matrix by a constant scales every entry in the matrix by that constant:
Answer:
89=14-5x
Step by step
Because 14 is how many he keeps and x5 is how many he gives to his cousins in total
30 x 30 = 900
This is the surface area of one side
900 x 6
Multiply by 6 to get the surface area of all 6 sides of the cube
900 x 6 = 5400