What are the conditions of direct variation?

Direct Variation. A relationship between two variables in which one is a constant multiple of the other. In particular, when one variable changes the other changes in proportion to the first. If b is directly proportional to a, the equation is of the form b = ka (where k is a constant).

Step-by-step explanation:

1. 6(3-8)-10

=6(-5)-10

=-30-10

=-40

2.30(3)+15(10)

=90+150

=240

3. 2(3)(3+32+32)

=6(67)

=402