Answer:
.86
Step-by-step explanation:
There are 5+10+15 = 30 students that earned and A, B or C
P( A, B or C) = number of students that earned and A ,B , C / total
=30/35
=.857142857
Rounded to the nearest hundredth
=.86
The unit rate is $1.97 per lightbulb. Multiply $1.97 by 7 to get 13.79
Unsure what you mean by diagonal right triangle
but if you wanted to find the hypothenuse (longest side) of a right triangle, you can apply pythagorean theorem

where c is the hypothenuse
a and b are the other sides