What am I doing wrong? I've tried every conceivable answer, I thought I knew this type of math well, but this program keeps telling me I'm wrong.

If a =6, what is the value of 2a(3b + 5c)?

Which equation shows the variable terms isolated on one side and the constant terms isolated on the other side for the equation -1/2x+3=4-1/4x? a. -1/4x=1 b. -3/4x=1 c. 7=1/4x d. 7=3/4x

What is the radius of the cone in the diagram? round your answer to the nearest whole number