Use Photomath it graphs too
Answer:
When two quantities increase or decrease together they are said to be directly. proportional
Bring the 13 over to read
13-12y-13=0
then move the 12y over do it becomes
13-13=12y
0=12y
y=0
The event that either M1 or M2 fails has probability

by the addition rule. Failure events are independent, so

so that

Denote this probability by
. Then
follows a geometric distribution with this parameter
and has density

The expectation is
.