Sunday

October 4, 2015
Posted by **Jamese** on Sunday, October 21, 2012 at 12:26pm.

- Math -
**Shell**, Sunday, October 21, 2012 at 12:58pmVariables,

X=first, (fixed) rate

y=second, rate(/minute)

t=time of call

z=total cost

Equation,

z=x+((t-1)*y)

Values,

7minutes is $10, 4minutes is $6.40

Plug them in, isolate one variable, set them equal to each other, and solve for the remaining variable,

10=x+((7-1)*y), 6.4=x+((4-1)*y)

10=x+(6*y), 6.4=x+(3*y)

10=x+(6*y), 6.4=x+(3*y)

-6y= -6y, -3y= -3y

10-6y=x, 6.4-3y=x

10-6y= 6.4-3y

-6.4=-6.4

3.6-6y=-3y

+6y=+6y

3.6=3y

(3.6)/3=(3y)/3

1.2=y

pick one original equation, plug in your new value, and solve for the remaining variable

10-6y=x

10-6(1.2)=x

10-7.2=x

2.8=x

Fixed first minute is $2.80, with $1.20 per each additional minute

I gave you the equations so that you could have them to help you on later problems. And I hope the directions helped.