An electrician charges $85 for a house call and $30 per hour for his services. Which of the following is a linear model of his charges.
A- y=30x+85
B- y=85+30
C- y=2.8+85
D-y= 85 to the power of 2.8

Asmall business produces and sells balls. the fixed costs are $20 and each ball costs $4.32 to produce. each ball sells for $8.32. write the equations for the total cost, c, and the revenue, r, then use the graphing method to determine how many balls must be sold to break even.

Another type of subtraction equation is 16-b=7. explain how you would sole this equation then solve it.

Each person in an it department of 25 people works on at least one of 3 major projects: system security, program implementation, platform development. 10 people work on system security, 13 work on program implementation, and 12 work on platform development. 4 people work on system security and platform development, 5 people work on program implementation and platform development, and 2 people work on all three projects. how many people work on system security and program implementation?